Sorry you are in this situation op.
But just thinking logically. He was so drunk he ‘can’t quite remember what happened’ yet he is ‘absolutely sure they didn’t have sex’.
It doesn’t make sense. He’s lying about being drunk, not remembering or having sex. He cannot be sure he knows what happened while not being sure what happened!
He cheated, he remembers, he is sanitising. Cheats are liars. He’s lied for 6 years. He’s okay with lying.
Think hard, does he lie about other things? Why he is late for work? Why he can’t see his friend? Why he was late phoning his colleague back? Or he may lie by omission?
Cheaters have a but in their fidelity. I am faithful but not if it’s on a stag night. I believe in fidelity but not if my wife won’t find out. I believe in fidelity but rubbing my penis against her isn’t really cheating.
I personally believe cheaters have a flaw that allows them to cheat. Low self esteem. Okay with lying. Poor boundaries. Inability to self soothe. Needing ego kibbles to feel good. Addictions. Lack of dignity/self respect. Okay with sneaking about like a teen behind a bike shed. Etc etc. I think that flaw becomes more apparent the more you watch him.
At the moment I don’t believe he is being honest (tho I have only read to the end of page one).
I do believe some (not many) but some people can recover the relationship. But sadly the personality traits that allow a person to cheat and break their own vows are the same traits that are incompatible with fixing the marriage.
I think that you can’t ever forgive something you don’t fully know about. It takes 3-5 years to heal from infidelity. Many split at the 3 year stage as that is when YOU stabilise and realise you are married to a man with poor personality traits. And unless he comes clean quickly and honestly your respect for him may vanish. Because being a liar for 6 years shows he lacks integrity. Because sneaky schoolboys who lurk behind bike sheds kissing their mates girlfriend weren’t an attractive option in year 10 never mind as a middle aged man.
You are the priority here. Nothing you did caused him to betray his own values. You are not that powerful. I don’t cheat on my husband for ME. Not for him, he’s annoying at times. I am faithful for me. I said I would be faithful in front of my family and friends and my words mean everything to me. If I cannot be honest with my vows then who am I? So I choose to be faithful for me. My husband is my collateral damage.