The elevator doors at the hotel slide open and Peter Odemwingie emerges with a spring in his step. He is on good form, laughing about spending a few nights with his wife and young son in the penthouse suite where Madonna once stayed and expressing his surprise that he has seen so little rain since arriving in south Wales. It is his new club, though, that has done most to put a smile back on his face. "I'm like a bird that has been let out of the cage," Odemwingie says.

Freedom came in the form of a £2.25m transfer to Cardiff City at the beginning of last week, bringing an end to a West Bromwich Albion career that started so promisingly three years ago but ended in such bitter acrimony. The deal went through a few minutes before the 11pm transfer window deadline, after Odemwingie agreed to sign the compromise agreement that Albion insisted was in place before releasing his registration.

The relationship between the two parties had long broken down and it is a measure of how bad things had become that a couple of weeks before the window closed Odemwingie served notice to terminate his contract citing constructive dismissal. He claimed he had been alienated from the first team, excluded from the pre-season tour, made to train on his own for a week on two separate occasions and forced to change in a private dressing room. Albion appealed.

"What the chairman [Jeremy Peace] did was very clever," Odemwingie says. "At the beginning of the transfer window he told me he wants to keep me but he needs to speak with the manager. I waited for three weeks. Nothing. He said he was on holiday, he had just got back. He kept saying: 'Tomorrow, tomorrow I'll speak to the coach [Steve Clarke].'

"I phoned the coach myself. I said: 'Coach, the chairman said he wants to keep me, I thought you said I can be sold, we have agreed there is no way back for me.' [Clarke] said he hasn't talked to the chairman and has only spoken to Richard [Garlick, the sporting director].

"They were playing a game to win time. The chairman didn't turn up again and then they said: 'The chairman will call you in the next 24 hours.' I was waiting with my phone. After that I said: 'Enough is enough.' I phoned the lawyers. We sought counsel's opinion, I had a big chance for constructive dismissal. They said: 'The relationship has broken down, you can put in a notice of termination,' so I did that on 16 August and gave them the reasons. On 30 August they appealed. A Premier League panel was set up, we were just waiting on a date."

For Odemwingie, the relief that everything has now been put to bed is mixed with a desire to tell his side of the story. An intelligent and articulate man, Odemwingie accepts that he has made mistakes but he says that he was not alone. He is, though, quick to stress that he does not want to be disrespectful to Albion or tar everyone at the club with the same brush. "The last six months spoilt a lot but it can't spoil everything," the Nigeria international says. "I can't have anything against the whole club when my fallout was with a few people."

When charting how things started to unravel at Albion, Odemwingie goes back to the moment in November 2011, when Roy Hodgson, the then head coach, publicly questioned his willingness to play through the pain barrier. Odemwingie saw those remarks as a stain on his character. He had a knee injury at the time – he posted a photo on Twitter to prove that was the case – and says he had agreed to cortisone injections on numerous occasions to get through games.

"I'm aware of the damage it can do and that it doesn't let you do full healing, but I came to England, I wanted to show everything I have got and I knew the team was normally one that could get relegated, so I said to myself: 'Anything it takes I'll give it,' and that's why it was very painful to take when Roy said it. But it was not only Roy, I felt it from the so-called hierarchy, that they were trying to put me under added pressure.

"My response was: 'Let me get well and I'm going to show it on the pitch when I'm fit.' I came back and started scoring and assisting goals, player of the month in February, scored the winner at Liverpool. But during that same season personal issues kicked in with a few team-mates and with one member of staff, Dean Kiely. He was nasty. We didn't say good morning for one and a half years. I don't want to have that in my life. Nevertheless, I always stayed professional – I want to play. Then Steve [Clarke] came and my feeling changed from a player that the manager was so desperate to have."

By the time January came around, Odemwingie wanted out and on the final day of the month he was confident he was about to become a Queens Park Rangers player. After meeting Dan Ashworth, the sporting director, and Garlick, who was about to take over in that role, Odemwingie was "100% sure the deal was happening. I said my goodbyes to everyone, even those who were not nice to me, I hugged it out before leaving."

The rest has gone down in deadline-day history. With the clock ticking down, players often drive within close proximity of a club before permission is granted – Gareth Barry admitted that he did exactly that last week with Everton – but Odemwingie's mistake was to advertise his presence by parking up outside Loftus Road and giving a live television interview at a time when Albion had not reached an agreement with QPR.

It was, the 32-year-old admits, an error of judgement, although he insists that he was not trying to force the deal through. He says he "would not even move a foot from Birmingham to London" if he had known it was crucial that Junior Hoilett moved in the opposite direction. He also feels that he was let down by his agents at the time.

After two hours sleep, Odemwingie drove into Albion's training ground. "On the morning of 1 February, Dan Ashworth apologised to me in front of Steve Clarke and Richard. He said: 'Peter, if I gave you the impression the deal was done, I'm sorry. Here is my phone with calls to Canada. I tried for it to happen.' I'm not going to claim I had written permission [to speak to QPR] because I didn't. But we were this close," Odemwingie says, holding his thumb and forefinger close together.

What Odemwingie did not take kindly to was Clarke's description of his actions. "The manager comes out and says it was 'total lunacy' [to drive to QPR]. In the country where I come from, with these kind of words, we don't take them lightly. The word lunacy cannot be associated with me. I am an absolutely normal person. 'Total lunacy' means you want to say that out of the blue I just appeared there without discussing [anything]."

A week later Albion issued a statement in which Odemwingie apologised for his actions and the club confirmed he had been disciplined and would resume full training with the first team and be available for selection. But in the wake of a goalless draw at Stoke in March, Odemwingie's patience snapped. He was aggrieved that he had been on the bench for a fourth match in succession and, not for the first time, took to Twitter to vent his anger. "Maybe I shouldn't have done it," says Odemwingie, when asked whether he regrets his tweets. "But nobody wanted to move on from what happened."

He went on to make three more appearances from the bench, the last of which was in the 4-0 defeat at Carrow Road in the penultimate game. "Everybody was unhappy and the manager asked everyone in the dressing room if anyone has anything to say. It was quiet. Then his assistant, Kevin Keen, spoke and blasted the team for a very poor performance.

"Then [Keen] finished. 'Anyone else?' There was nothing and then I said: 'Yeah, I want to say something.' I said: 'I'm not sure if I'll have an opportunity again to speak with my team-mates, because I will probably be sold this summer. I want to apologise to Steve for, in his first year as a coach, having to deal with more issues outside of football than he should. But when he took over the job he knew what issues we have in the group and those were reasons why I wanted to leave.'

"And then I just asked a few players why I was the only one they used specific language to in situations and behaved in a way only to me. I only asked. After the players, I said to the doctor: 'You know me very well, my character and my dedication to football, I'm not a prima donna, you inject me all the time. You were very wrong to let Roy say [what he did about me].' And I said to the goalkeeper trainer, Dean: 'I don't know what your problem was since the beginning of me being in this club.' I said if it was the same words and actions towards everyone, no problem. But if it's only towards me, it's personal."

Albion responded by barring Odemwingie from training with the rest of the first-team players in the final week of the campaign and that treatment continued when he returned for pre-season. "The first day I came back, Richard Garlick said: 'There is a special dressing room, a personal dressing room only for you.'"

With no locker to clear, Odemwingie's exit was much more low-key the second time around and he was not about to repeat the mistake he made with QPR. "My agent told me they have the agreement, they are allowed to speak to you, you can come for a medical. I told him: 'Listen, until I have it from West Brom, I'm not going anywhere.'"

It is hard to escape the feeling that everyone has lost out. Odemwingie could have been an Albion legend – he scored 30 Premier League goals in 87 appearances, including a hat-trick against Wolves in a memorable 5-1 win at Molineux in February 2012 – and the club could badly do with the striker who was a breath of fresh air when he arrived from Lokomotiv Moscow.

Odemwingie pauses for a long time when asked how he thinks the public perceive him. "Stubborn maybe," he says. "But you know what, I don't think you can damage a reputation so fast, because until January, for West Brom fans and for the league, I was the perfect person, I like to speak to people, I'm not selfish. I have a temper and lost it maybe on Twitter but it piled up on me and it was too much. The issues were unresolved."

At Cardiff, he hopes to put everything behind him. "I realise that it is a lot of pressure, because I have to show I didn't lose it after six months. But I'm going to be lighter in the head," says Odemwingie, who claims he has not looked at the date of the Albion fixtures. "I'm still a good player for a Premier League club and a good man to have in the club."