The couple hit headlines in December when reports surfaced suggesting McDermott had cheated on his wife of seven years while he was in Toronto.
Following the news, McDermott checked himself into a treatment facility and subsequently admitted the reports were true in a promo for their new reality show, True Tori.
Now Spelling is speaking out to tell of her despair over her husband's infidelity.
The former Beverly Hills, 90210 star tells UsWeekly magazine she found out about the affair from an aide before it was made public, saying, "We put all four kids to bed and went into our bedroom. I said, 'I didn't hear it from you first, but I deserve to hear it before the world hears it.' I laid on my side (of the bed) and he laid on his side and he talked me through the entire week with (lover) Emily (Goodhand). He didn't get graphic; I didn't want him to. We kept it to facts....
"He went to treatment (the next morning). I didn't kick him out. He decided he had hit rock bottom. He had hurt me and the family, and it all crumbled. He needed to go away and work on himself..."
McDermott has since completed his treatment, but Spelling reveals she is uncertain about the future of their marriage: "If I can't ever let my guard down again, then there can't be a relationship... Whether I can trust him again, that's the big question... I feel better now, getting it out, getting it off my chest, talking it through. We're parenting and figuring out if there is any relationship to be saved. I have no idea. Whichever way my marriage goes, though, I finally have my voice back and can be honest. We'll see what happens."