Ask yourself these questions:
What are you afraid of?
Why do you feel obligated to stay?
Why do you feel guilty about leaving?
Also, what would your life look like without these things to think about?
I saw your response and have been thinking about it for a couple of hours.
I can't put my finger on what I'm afraid of so I'll start with what I'm not afraid of. I'm not afraid of being without a SO, I'm not afraid of living alone, I'm not afraid/worried about money issues living by myself, I'm not afraid of what friends/family will think if I leave.
I feel obligated to stay ... . why? Good question. I feel like I really want to have a happy life with uBPDbf. I can remember how good things were before we lived together. I want that man back, but I know he no longer exists. He disappeared, literally, within one week of us living together and its been a struggle for the last 4 years.
My guilt about leaving - I definitely feel guilty about leaving someone who is so screwed up in the head. If I leave, he'll never understand that I really do care about him but just couldn't live with his rage, unhappiness and obsessive jealousy. I also feel guilty about leaving because his 2nd wife walked out on him for just the same reasons.
I know he's hurting like crazy deep down from something in his past, other family members have commented on it also, and I just feel bad leaving someone who's in such pain even though he refuses to help himself. I've suggested counseling so many times but he refuses. I know you can't help someone who won't help themselves. I know that.
So really, I'm back to square one. I want him to change or at least go back to who he was (which I know I can't make happen) and I want the kind of r/s I know I can't get from him (support, respect, "normal" conversations, a life that includes my family and friends).
Without all this craziness (I can't think of a better word) in my life, I know I'd miss him, probably for a long time, but I also know that I can make a happy life for myself, which is all that I want - with him or without him.
P.S. Thanks Val78 for these questions, they really made me think, deep down, about my life with him.