Since you are separated and living apart, there's not much you can do about the "affair". You can't control what he does and if you raise the subject w/him, he will deny it or gaslight you about your paranoia. He will turn it around and accuse you of doing it too.
If he comes sniffing around and wanting sex w/you, be sure to use protection. There have been a few cases where the spouses contracted a STD from the wandering spouse.
Sit quietly and patiently, more will be revealed to you in due time.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.
