Sorry you're having a bad day, faffa. Big hugs. I know it may not be helpful to hear now, but in some ways I think it is a positive thing that you are feeling today that it's not going to work out. Not because I want you to feel awful, far from it. But the fact is, it shouldn't work out, if he stays the way he is. It is only if he can address the issues with you, focus on you and your healing, that you should stay together, 28 years or not. And it is the paradox of these things, that when you are actually willing to step away because, for you, it is unacceptable, that the penny may drop, and he may realise it's not all about him.
Also, I'm sorry to say, if you feel that there's more that you don't know, there probably is. That doesn't mean there were many full blown affairs, but as others have said, at a minimum your husband's previous behaviour (confiding in the female friend - vastly inappropriate; a younger colleague who was "in love" with him - yeah, right, the fact that was expressed to him in any way is a violation of about 100 boundaries, even if you take that at face value) is highly, highly questionable and hugely disrespectful. That is behaviour that is basically going to take a metaphorical knock upside the head to change.
All this doesn't mean it won't be fixable. But I second the advice above to get yourself into therapy and figure out what you want and need. Your husband hopefully can give that to you, but once you are in a place that you are firm and accepting of what you need, only then will you have a chance at a healthy marriage going forward. Please keep repeating to yourself that your marriage is not on his terms, especially now. This is your life, not some practice run. He can either make you happy or not, but that's on him, not you. You decide from there.