You need to protect your child. He has shown you twice that he has these sexual urges related to kids. I can understand your Christian views regarding marriage, I feel the same way. I think there is a certain point at which you must say, enough.

God says divorce is something we can do if there is infidelity. He has (mentally) and physically cheated on you many times. I would go to therapy yourself and really, really talk to a qualified counselor, not just your pastor about this.

I was sexually abused for years and it made my life hell, as much as you want to make your marriage work, do not put your child in harms way. Sexual predators do not change, they talk a good game, but those urges remain in them.

You have a tough decision to make. Listen to your gut.