please no bashing

I've fallen for a guy who has a girlfriend. Yes I know that's the worst thing I could do. Yes I know it's wrong and not fair to her. Yes I know we shoud have stopped it before it led anywhere inappropriate. My question is, if he says all the things he does about how he wants us to be an actual us he just doesn't know when and all the things you can imagine him saying which is amazing and I've never felt this way about a guy he says it's the same way for him....is he actually going to leave his girlfriend to be with me? Like he actually could be telling the truth about how he feels about me? Or am I stupid and they never leave and we could never be happy together?😞