Ugh. Sorry you had to go through that.
The thing that stood out in your post to me was:
He always is able to find a way to make me believe that it isn't that much or that bad
My thought was, uh, no, you are letting him convince you because you want to believe. That's what codependency does to a person.
I hope that you can figure out how to help yourself break the cycle you have put yourself in. He doesn't seem willing to change, but you can be willing to change yourself and your part in the situation.
I wish you all the best.