Don't email him. Write it for you.
He's history. Don't spend energy you need to use on sorting things out for you, on him.
If you email him, you'll just open up another exhausting round of either argument or (more likely) him taking the opportunity to trot out his usual nasty set of comebacks. And this will just waste time, upset you, and also possibly alert him to the fact you're serious. This last is important. I can tell you now - the worst headfuck is still to come here. When it dawns on him that you've reached the end of your tether, he will do a 180 degree turn. Because he doesn't really want you to 'fill your boots'. It would be a disaster for him. He'd lose his comfy position as getting to be part of a family, being dad, having his pants washed and having someone else to pick up the slack, and he'd have to shift for himself. The only reason that he's so utterly nasty to you is because he thinks it's safe to do so, because you're too scared of the alternative to leave.
When he sees that you aren't, he will go on a full-out charm offensive to stop you. Not because he is sorry and loves you, but because he does not want to lose the comfy set up.
This will be really upsetting and a major distraction. So don't invite it until you have to. Get yourself sorted- jobs, applications, checking out housing options- maybe you'll move a wee way away even. Do all this before you alert him because when you do, he will do everything he can to berate, threaten, charm, confuse, guilt and bamboozle.
Get yourself sorted so that you can tell him you're going and go within a short space of time.