You know, I had a temper problem for most of my life, especially around that time of the month, although that is no excuse. My H and kids put up with it for years. But, they never thought I was a bad person. H started A long after I stopped the temper tantrums. Several years into the marriage, I found a way to stop wanting to always be right, I wanted peace in my home. So, I understand anger, temper, etc. The red fog.
Okay, that's my similarity to you. One thing that disturbs me about your H is that he never actually came to you or tried to get help. He wrote to your mother, but what did she do? Did he ever tell you that he was going behind your back and talking about issues in your M? Yet, he wants you to keep his secrets? Something must've been bothering you for you to be that way. Was you H starting to give signs of retreating from you before you became this "horrible" person.
Give yourself a break and know that not all the problems of the "world" is your fault. Nothing excuses what your H is doing except that it is an addiction, possibly. You cannot cause that, although that may be how he is justifying it in his mind. I wonder how long he has been in this lifestyle? Probably a lot longer than he says and what you know.
No matter how much we think we know the person closest to us, there is always room for secrets. I could not believe the things I discovered about my H. After 24 years of marriage, I still don't truly know him, and I sure don't trust him fully anymore. But that's okay.
Just take a break, calm down, and think things through. You will probably find that most of the badness you attribute to yourself was something he accused you of, which doesn't mean it's true.
Me:57 H:52 M:28 Got another lawyer last year and filed. D35,S/D twins28,D22 EA4/04 End? Who knows? "Life is like a mirror. Smile at it and it smiles back at you." — Peace Pilgrim