OP, this was me around a year ago. Christmas 2011 everything came to a head and I told my husband I wanted a divorce, his response 'Why, you've got no grounds!' He'd been diagnosed with stress, then depression, then come off the anti-depressants cold-turkey and turned into a complete lunatic.
His behavior killed all the love that I used to feel for him, and for months I would drive to work every day in tears chanting to myself, 'you can divorce him' over and over.
It felt the way that I imagine you might, I didn't want to be with this man anymore but I also didn't want to be 'the bad guy' and leave him when he was unwell and it wasn't his fault. In the end I decided that if he had so little self-respect to insist on staying with someone who wanted out then I would make the most of it. After all I could do what I wanted and if he decided he wouldn't take that anymore I got what I wanted. I drew my line in the sand, I knew exactly how much I was prepared to take and under what circumstances I would decide it was truly over and leave him, although I never told him about it he's managed to stay on the right side of the line so far.
After that I took back control of my life, he rarely goes out anymore, his choice, so I have regular child-care whenever I need it, ds2 is 8, if there's something I want to see at the cinema I go see it, I've joined a Martial Arts club and generally go 2 or 3 times a week which has done wonders for my self-confidence. I've taken up running, I'm doing a half marathon later this year. I write fanfiction, I work full time and I love my job.
What I've found is that since giving up on caring what my husband thinks or feels, I'm now actually happy, which was quite a revelation when I realised it, and whilst I doubt I'll ever again love him the way I did, things are definitely getting better, I certainly don't hate him anymore either.