I'd advise not contacting him. If he contacts you, tell him what you expect from him: To cut off all contact with OW. He claimed to have chosen you, right? Tell him actions speak louder than words. If he is serious he will cut off all contact, and become transparent with you.

Make it all about the respect you and the marriage deserve, not about the hurt he has caused you. Do this without throwng down an ultimatum.

M: A really long time.
Crisis: 5 years.
She's still worth it.

Life is never made unbearable by circumstances, but only by lack of meaning and purpose. -Viktor Frankl