If this is MLC, it is the child h who is having the affair not the adult h. He needs to work those childhood issues out to grow up. It is his best chance at getting through this.

The OW is never about you. You can try to stop the A but those issues will still be there lurking. And if he stops, each time he goes back it will be worse. These are his issues to resolve.

Focus on you and your boundaries.

Me 41, H 47, M 15 yrs, S11, S13
BD 1: 11/4/14 we work on it; really I pretzel myself
BD 2: 3/31/15 H goes down to "dorm room"
8/15: H back to MBR
10/15: H back in dorm room
1/18: H files, now divorced