I'll offer my opinion on your question. Only YOU can decide how long you are willing to be in limbo. When I discovered my W's A, I took a week to decide what I wanted before confronting her. When I did confront her, it was calm and I told her she needed to gather her things and leave the house immediately. She did. I never told her she needed to stop the A. But I did tell her that so long as she chose to engage in an A, that she could not stay in our house. I actually didn't want her to leave. I wanted to see remorse and then we would start working on the mess that had been created. But that's not what I got.
In the end, it was me filing for D that caused the A to end. OM knew I filed and probably felt I would be telling his W in short order. So he manned up and confessed. That is what finally ended the A. But if you go that route, you need to truly be ready to end it all. It can't be a scare tactic.
Me: 48 y/o W: 47 y/o Together: > 20 yrs BD: Dec '15, then S 2nd BD: Mar '16, then I filed for D April '16: started piecing
