You don't have to show him trust if he hasn't actually earned it. He hasn't done a whole lot to reassure you that he never had anything with OW. His suddenly say ILYBINILWY is, as far as I'm concerned, reason enough not to trust. Men frequently are cheating or at least want to by the time they drop the bomb.
That being said, your behavior over the past 10 years of accusations is wrong. You can choose to swallow your accusations. You can just make the assumption that he isn't cheating and go forward with your life as though he isn't. You've lost a lot by your continued suspicions and won't lose a whole lot more to just say, "I can't control that anyway. Accusing him doesn't work. So I might as well just treat him as though he has my trust and if I'm fooled, I guess I lived and learned."
You cannot be lonely if you like the person you're alone with. Dr. Wayne Dyer
