Beware: I'd call it quits with this guy. If it's serious things that he's depending on you and not his spouse for, it might be emotional cheating. I fell into that trap-it's a little bit of a self esteem booster to have someone comfortable going to you to talk about the deep shit, and it's easy to get attached and want more of those good feelings. I didn't know that he had been coming to me first about stuff and that he was telling me things that he wasn't telling his wife. I just thought we were close friends, but I learned an important lesson about being friends with people who are in committed relationships and you're the gender they're attracted to. If it is emotional cheating, it only ends in pain for all three of you. Might be worth asking "have you talked to your partner about this?" If he's trying to flatter you with "they wouldn't understand," RUN. Or if he wants you to do emotional labor he should be doing himself, another sign to call it quits.

Also something important-if you're depending on each other, he's getting the benefit of being married to a committed partner AND having an additional emotional relationship, and you get no benefits. Just someone who can't care about you in a way you deserve. If you're preoccupied with him, you won't be looking for actually single people who can fully support you. Just thoughts from someone who's been there before!