I'm so sorry MemoryLane. It's hard when you're done but living in limbo. You've given him more than enough chances. It's okay to let go for your well-being. Nothing changes if nothing changes.
Your first step should be, as The1stWife said, to start practicing detachment. Remember the acronym (Don't Even Think About Changing Him), accept that this is who he is, and work on letting go of any feelings of love. Aim for indifference. Anger, cruelty, and sadness are all feelings that still engage with attachment. It will take time before your feelings really start to disengage, but you'll get there.
The next step is to talk to a lawyer or three. Many will do free initial consultations. Find out what you can expect in terms of custody, splitting finances, keeping vs. selling the house, etc. If you truly can't move right now, you can start saving up in a separate account. You don't have to tell your WS about that account until you do your financial disclosures during the divorce. As for the summer holiday, you can wait to file for divorce until after. Even after you file, you'll probably be under the same roof for some time.
It might not go as badly as you fear. Check out the Fear vs Reality thread pinned to the top of this forum.
Divorce is really really hard. I can't say any of it is enjoyable or easy, but I will say that I have so much more peace now, and even though I'm sometimes sad about seeing my kid less, I'm able to be so much more emotionally and physically present for her when I do see her. I feel worse about the years I spent in my head, depressed, crying every night - all that energy spent on my issues that I could've poured into her instead.