KANSAS CITY, Mo — Chiefs linebacker Jovan Belcher leaned over his mortally wounded gal pal, kissed her on the forehead and apologized to his mom, before fleeing to team headquarters and killed himself, according to published reports today.

Belcher appeared to understand the gravity of his actions on Saturday morning immediately after blowing away girlfriend Kasandra Perkins, mother of his 3-month-old daughter, according to a dramatic narrative painted by the Kansas City Star newspaper.

Belcher’s mom, who recently moved from Long Island to Kansas City to help care for struggling couple’s girl, reportedly witnessed the tragic goodbye.

After kissing Perkins’ forehead, Belcher apologized to his mom, kissed his daughter and then took off for the Chiefs’ practice facility at 8 a.m., according to the Star.

That’s where he shot himself in the head with a different gun in front of the team’s coach and general manager.

When Belcher reached team headquarters, he got out of his car with a gun in hand, came upon GM Scott Pioli and said “I did it, I killed her,” police told the Star newspaper.

Belcher specifically asked to speak to his coaches before ending his life, according to Sports Illustrated.

“I came here to tell you thank you,” Belcher told Pioli. “Thank you for my chance. I love you, bro.”

Chiefs coach Romeo Crennel and linebackers coach Gary Gibbs arrived a short time later and Belcher reportedly said, “Guys, I have to do this,” according to the Star.

“I was trying to get him to understand that life is not over,” Crennel told the newspaper. “He still has a chance and let’s get this worked out.’’

With police sirens blaring in the background, Belcher walked away from the men.

“I got to go,” Belcher said. “I can’t be here.”

Belcher dropped to a knee, made the sign of the cross across his chest before shooting himself in the head.

Hours earlier, Belcher had a boozy dinner with another woman and spent the night at her apartment before going home, sources told The Post yesterday.

After dinner and drinks Friday night at a local tavern, the Long Island native Belcher took the woman, Brittni Glass, to her home, but spent the next several hours asleep in his Bentley outside her building, neighbors said.

After cops roused him from his drunken slumber at about 2:30 a.m., Belcher went inside Glass’ building and re-emerged about four hours later.

“I was with him that night, that’s it,” a reluctant Glass told The Post.

Belcher drove away at about 6:45 a.m., making the 10-minute ride to the home he shared with Perkins.

The couple fought and Belcher’s mom reportedly told cops she heard her son say something to the effect of: “You can’t talk to me like that!”

Chiefs officials knew about the couple’s ongoing beefs and provided counseling, Kansas City police Sgt. Richard Sharp said.

Cops confirmed that several people came forward to tell them about Belcher’s visit.

“His Bentley was parked outside,” a neighbor said. “He went upstairs. He was drunk. He went up to see the girl.’’

Early reports said Belcher flew into a rage after Perkins returned late from a Trey Songz concert at about 1 a.m.

But according to Glass and her neighbors, Belcher wasn’t even home then.

Residents said they had seen Belcher — who had a $1.9 million contract with the Chiefs this year — and his distinctive black Bentley at the building several times in recent months.

Glass said she and Belcher were not in a relationship and declined to say exactly where he slept.

Meanwhile, a new report said Belcher had been violent in a past relationship.

In 2006, while a grid star at the University of Maine, he punched his fist through a window because he was “upset with a girl,’’ said a police report obtained by USA Today.

Less than a year later, campus cops responded to a complaint of disorderly conduct at a dorm after someone “became concerned about the raised voices” of Belcher and a girlfriend outside his room, the paper said..

Yesterday, Perkins’ family broke its silence for the first time since the tragedy.

“Our wish is for Kasi to be remembered for the love she shared with us all. Kasi will be truly missed,” they said in a statement.

As some people questioned why Belcher needed a gun — much less two — some teammates defended the right.

“If you have daughters, you should [have a gun],” said defensive lineman Shaun Smith.

Linebacker Brandon Siler, who had Thanksgiving dinner with Belcher, added, “Most of the time, they’re for self-defense or sport.”

Additional reporting by Leonard Greene, Selim Algar, David K. Li and Post Wire Services