Northern... on behalf of myself as a survivor of abuse... goddamn... I'm sorry that you've had such a rough go of it. I'm at work right now and can't write much. I'll touch on a bunch of issues that you raised in a bit.... But I want you to know that this site has been so helpful to me. Your posts have been so helpful and healing for me. I had a wonderful evening with my wife last night, and if I can do it, you can, too.
Just one thing before I go. Don't think that your husband is having some wonderful relationship with the "other woman." It sounds to me like he's neck-deep in his abuse. If you want to see something about as shame cycle, look up one of my other posts this morning. The BDSM stuff, by the way, I hope, will eventually crack you up. (Make you laugh, not go crazy!) I mean, come on. It's just sex. If you want leather, break out the leather. Who cares? But it's not about that. It's about shame, secrecy, abuse, fear of getting caught....
And that's what your H carries with him. Honestly, my heart goes out to him. But mine can. He never hurt me. I think CdnDW is absolutely right.
Keep posting. You're an important contributor here. You can heal here. You can be safe here. Good luck.