It's more likely his wife is fighting for the marriage. Men get manipulated, usually through sex. None of it has anything to do with you, and the dude probably isn't intending to hurt you. He's caught in the middle. When things are shitty with the wife, he will turn to you.

It's a roller coaster and it's difficult. There's a good chance he means well and isn't insincere towards you. If he really wants to fix the marriage, he should confess his behavior, and see where that lands him. If the wife still wants to keep him and that's what he wants, then you should let him go. If the wife dumps him, then you could pick up the pieces.

It's possible to love more than 1 person. He might be stuck. Don't take it too personally. He very well could have meant every word he's ever said to you. Don't underestimate the power of the wife to manipulate and control him. It's also possible she knows everything, and is making an effort to make things work. There's nothing you can do about that.

You get to decide how much you can handle. When it's too much, let it die and accept it. I know what it's like to hang onto and hope for someone that you can't have. It's miserable and feels like torture. In the end we only torture ourselves. You are not alone in your suffering. God bless you.