Simon Barney, the ex-husband of Real Housewives of Orange County star Tamra Judge, opens up to PEOPLE exclusively about his stage 3 throat cancer diagnosis and how he's staying positive throughout his health battle

Simon Barney is facing a new reality these days, far away from any Bravo cameras.

The father of three — who was married to Real Housewives of Orange County star Tamra Judge for 13 years before their split in 2011 — has been diagnosed with stage 3 throat cancer, he tells PEOPLE exclusively.

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“I’m a private person, despite what my time on reality television might say,” Barney, 55, says with a laugh. “But I wanted to speak before someone else does and uses their words, not mine. And to speak out about it so others can see how I’ve taken this fight on with optimism, and the good this has ultimately brought my life.”

“I think everything happens for a reason, I think your destiny is pretty much set for you, and you’re here to learn lessons,” Barney adds. “This has been a tough lesson for me. And I’m hoping it can be a lesson for others, too.”

Barney first started experiencing symptoms in May when he noticed his salivary glands were swollen on one side. Initially, doctors thought it was just an infection, but an ultrasound and biopsy found other areas were affected too, including the side of Barney’s neck. The final diagnosis was cancer.

A follow-up appointment, accompanied by his fiancée of 9 years Catushia Ienni, with new top doctors found the cancer had spread into Barney’s throat, tonsils and lymph nodes.

They considered surgery, but a biopsy showed the cancer was too spread out. A second and third opinion produced the same results: Barney would need to go through the dual treatment of chemotherapy and radiation.

Image zoom Simon Barney Courtesy of Simon Barney

Image zoom Simon Barney and Catushia Ienni in 2018 Courtesy of Simon Barney

At first, Barney decided not to share the news with coworkers and friends until the beginning of January, when he kicked off his treatment plan.

He says he let his family know before that, including Judge and their three children: son Spencer, 19, and daughters Sidney, 21, and Sophia, 14.

“He told me the news and we both literally started crying. I just couldn’t believe it,” Judge, 52, tells PEOPLE, breaking into tears as she recalls their talk, which she said happened at a local Starbucks. “My first thought was, ‘I don’t want to take my kids to their dad’s funeral,’ and immediately, any ill feelings between the two of us just vanished. At the end of the day, none of that matters. All we have to do is rally together to make it through this.”

The conversation changed things in Barney’s family, which had been struggling in recent years. Judge and her daughter, Sidney, began communicating again, as have Barney and his son, Spencer, after years of estrangement. Barney’s also seen an increase in contact with Ryan Vieth, 34, Judge’s son from a previous relationship.

“It’s kind of like a new beginning for me and my family. It’s really brought everyone closer together,” Barney says. “When I told Tamra, she said she cried for like, two or three days. Things changed with our relationship from there, in a good way. We’re getting along in ways we haven’t in years. And she’s become close with my fiancée. And that shift carried across the board with my kids, too.”

“That’s what I’ve always wanted,’ he continues. “My fiancée, the same thing, she’s always wanted that with my ex-wife, for the kids. The kids would prefer it if we all got along. And they see that now, and it’s had such a powerful effect.”

Image zoom Simon Barney and Tamra Judge in 2008 Katy Winn/Getty

Doctors have placed Barney on an aggressive treatment schedule, doubling up with radiation and chemotherapy at the same time. His chemotherapy is every 3 weeks, while his radiation is every day — 5 days a week — for a total of 7 weeks.

“The process is the real bad part,” Barney explains. “It basically attacks all of your organs. You’re like poisoned. It’s been killing me. If I had a choice, I probably wouldn’t have done chemo and radiation at the same time, but that’s what they recommended. It’s like hitting your head with a hammer and pouring gas on yourself. I was ready to end it the other day, the symptoms were so bad. It’s almost worst than the cancer.”

“You go in Monday, you get the chemo. By Friday, Saturday, Sunday, all the steroids are wearing off that they give you, and it really hits you,” he says. “I just curl up in a ball for the whole weekend in my bed, and then pray that the truck gets off me. Because I was run over by one.”

“Then they give you a shot that’s supposed to help your white blood cells multiply, and that hurts your bones, so you feel like you can’t walk,” he adds. “And then the radiation, basically they hit me in my neck, my throat, and the tonsil area. It’s like a 9 out of 10 pain. It’s a lot of pain.”

Image zoom Simon Barney, during a 2018 trip to Paris Courtesy of Simon Barney

All of this has left Barney barely able to eat. “You have an appetite but you can’t eat anything because your taste buds are gone, or they taste and smell like chemo — this metallic, disgusting taste and smell,” he says. “My throat is swollen and bleeding which makes it difficult to swallow even water.”

He’s experienced other side effects as well, including constant buzzing in his ear and slight hair loss. But surprisingly, what hasn’t gone is Barney’s positive outlook on life.

“I have hope,” Barney says. “Doctors have said I’m doing really well so far. They look at me and they go, ‘Man, you don’t look like you’re going through chemo.’ So that’s good, the prognosis is good.”

“I’m a huge optimist; the glass is always half full, not half empty. And I’ve always been that way, the cancer just enhanced it,” Barney says. “I’m kind of a jokester. And everyone in my life has been so supportive and offered to drive me to treatments and take care of me, but my whole motto is, ‘Don’t treat me like a cancer patient because that’s not how I want to be treated.’ So I stay strong and don’t let this take me down. Because if your attitude sucks — if you start believing, ‘Oh my God, cancer’s a death sentence’ — then you’re done.”

“I think, if you had to pick out of from all my family, I was the right person to get it,” he continues. “I can survive this, at least mentally.”

And if he can’t physically survive it? Well, Barney’s thought that through too.