What Do I Do? (Repost)

So my father has recently decided to leave his second wife, after eleven years together. I've never liked her, hated her in fact, and approve of his decision. She's verbally abused him for the past decade and generally made his life a living hell. But he can't seem to get up the courage to actually leave. He talks about it, makes plans, but at the last second breaks and never goes through with it. I've tried being here for him and tried to help him and give him advice and courage, but nothing I do seems to make it through to him. I've talked to him, told him all of the verbal abuse I've suffered over the past several years, and that should be enough. No one should stay with someone who calls their daughter a whore, fat, ugly, etc. That's not how it should work, choosing to ignore what your spouse says to your child. The child was there first, long before the second wife. She's controlling, never letting him out of her sight, and she's generally broken him down to almost nothing. There's just no fight left in him. And I want to help, he's my father. But now he's asking me to put everything in my life on hold for the immediate future, take time off of work, stay at his house with him, cancel all of my plans I have for the holidays to help him get out. I've already put so much into trying to help him and I'm mentally exhausted, I haven't been sleeping because I'm waiting for him to figure it out if we're going to leave or stay and when. I can't do it anymore, and I need to just tell him that I can't keep doing this. I have a life of my own, a job and a fiancé, friends, everything. He doesn't seem to realize that, and despite being firm in my beliefs of telling him my opinion and leaving him to straighten himself out, I still feel guilty. I don't even know how I should feel anymore, I'm just so emotional from being tired all the time that I feel strung out.