Don't lose hope.
Honestly I have the same condition he has. Perhaps not as bad, but it began to show up after highschool and I started my life.
He's probably been this way for so long he doesn't know how or even want to change it.
I have taken almost every med for my sever anger problems. And yes it mostly goes to my wife, I don't physically hurt her, although sometimes I feel like it, and I am always thinking she's sleeping around, and even want her to do everything.
Luckilly we got help, and finally found a medication that controls anger and irritability.
I am no Dr. but I suggest Wellbutrin XL, not SR. For me and other I know with the same problem this was a complete life saver. It's worth a try, and unlike Paxil there arent' any sexual side affects.
He may also need something to help him relax even more like valium. Although Valium does nothing at all for me, even in dangerous doses, that could just be me, and not related to this anger outburts.
If you still care for him and he's willing to try the medication give it a chance, for the most part he probably can't help it, I know I couldn't control my anger even with strong mental discipline until I was on Wellbutrin XL. I said XL instead of SR because IMHO it works better, and there is no generic for it. I have taken Wellbutrin SR, it worked great, THEN they came out with a generic brand of it, and I was forced to use that, and it did NOTHING. So stick with Wellbutrin XL since there is no generic.
You are not the evil one here! You have become a punching bag. run for your life! 12 years is more than enough of trying to save a relationship.
If you are afraid of a physical attack by him, then you have to do it very carefully. Otherwise you just have to say your piece and tell him what steps you are going to take to separate your life from his. There is nothing evil about this kind of incompatibility, and you don't have to take abuse. But if there is something still there, then you ought to tell him that he has to go to couples counseling with you, through the church or through a professional in the community.