The Chopped Canada host opened up about the marital struggles he and the former Beverly Hills, 90210 star faced prior to their breakup, sharing that had been "having problems" for a while but "it just got worse" when they started sleeping in separate bedrooms due to the family's large brood of pets, which included several dogs, a pig and a chicken.
"We know dogs have accidents, and our particular dogs were having a lot. And I just couldn't deal with that anymore," McDermott recalled in an interview with the Daily Mail published Nov. 15. "So, I created a healthy boundary for myself and I said, 'I can't do this. I can't live and sleep in this kind of condition.'"
At one point, the 56-year-old noted, the pig was sleeping in the couple's bed and the chicken was living in their bathroom.
"I drew that boundary for myself and moved to another room and things just progressed from there," he shared. "There were no efforts to sort of remedy the problem to get back into the room."
During that time, McDermott said he was also struggling with an alcohol addiction that further distanced himself from Spelling, with whom he shares kids Liam, 16, Stella, 15, Hattie, 12, Finn, 11, and Beau, 7.
"I just isolated more and more and more and she isolated with the kids," he remembered. "We were roommates. Rarely, rarely, rarely did we eat together. We'd sit down and have a family meal but it was always disjointed."
Acknowledging that he played "a big part" in the fallout, McDermott—who is also dad to son Jack, 25, with ex-wife Mary Jo Eustace—said he and Spelling, 50, lacked intimacy toward the end of their relationship.
"I believe that the marital bed is the docking station for your relationship," he explained. "It's where you're intimate, it's where you love. You laugh and you cry. So that's gone. The relationship suffers greatly, greatly. When you're in a roommate situation and there's no connection or intimacy, what do you expect is going to happen?"
The Due South alum added, "I've never been so lonely in the same house with six other people, never been so lonely in my life. I didn't know how to get out of the situation I was in. I was hurting. I was heartbroken. I was depressed. I hated myself."
McDermott announced his breakup from Spelling in June, writing in a since-deleted Instagram post that the pair "decided to go our separate ways, and start a new journey of our own."
"We will continue to work together as loving parents," he wrote at the time, "and guide and love our children through this difficult time."
Since then, McDermott sought treatment for his addiction issues with help from Spelling. As he put it, "She came from just such a place of love and wanting me to be healthy and happy."
The Pretty Hard Cases actor has also seemingly moved on with account executive Lily Calo, as the pair were seen holding hands in October. Meanwhile, Spelling was recently linked to photographer Ryan Cramer after the two enjoyed a PDA-packed date in Los Angeles.
E! News has reached out to Spelling's rep for comment on McDermott's remarks about their marriage but hasn't heard back.
Keep reading to see the couple's family photos through the years.