Did spitfires words ring too true? I wanted to say this- I don't doubt your DH is a good guy, but he IS a mama's boy and he's putting his mother and family first before you and your marriage.
You say that if he were to turn his back on his family, or turn his mom in (I can't remember exactly what you said this in reference to) that your marriage would be over. Do you really think your marriage is strong enough to make it if things DON'T change? YOU hate his family, YOU can't stand them, YOU have a lot of anger towards them. You think this is a recipe for a long, successful, happy marriage?
But your DH, being a "great guy", doesn't want to turn his back on his family at all - and you're only more angry about it.
Do you see what a corner you're backed in to? You need to stop relying on "oh- he's such a good guy" and you need to start holding HIM responsible for the role HE is playing in all of this. Yes- so much of this is his mom and his family, but he plays a role in it too and as long as you let him off the hook because he's such a "great guy" - I dont' see how you can have a long, happy marriage. Teh resentment is only going to grow.
I genuinely wish you luck because right now I think you're in a total lose- lose situation.