I've just been reading through the posts since Friday....
It strikes me that you are moving forward, even if you can't see it yourself right now.
There are times when you've described the life you'd want for yourself after leaving him. If you're still only able to let yourself think or write about them as hypotheticals that's fine, as long as you let the idea grow.
You seem to be starting to be able to step back and watch his behaviour with more of a distant critical eye, rather than responding emotionally and getting dragged into the cycle of abuse.
I don't know if it helps, but when I was struggling to keep my head together I used to mentally step back and start labelling where in the cycle of abuse he was (mainting control? Regaining control? Etc) and labelling the tactics he was using.
You asked what is the difference between abusive and short tempered. You had excellent responses. I'd add, the difference is that if he was short tempered he would "lose" his temper with everyone, everywhere. Not exclusively with you, at a home. The latter indicates somebody who is actually controlling their temper exceptionally well.
One of my turning points was when I stopped saying he had "lost it with me" and started saying he had "kicked off at me". I didn't make him lose his temper, he chose to use manufactured rage to get me to submit.
If things are "worse" it's because you're not complying like you were before. So he is ramping up the abuse to try and regain full control over you. That's how it works. Rules of the game.
As much as it was encouraging to read you reflecting on the ingredients you would need to live your life after he is gone, I feel I need to point out that trying to build up your self esteem when you're living with somebody who is abusing you and trying to break your self esteem is much like trying to build an igloo in a desert.
On that theme, I'm not so convinced that you would be lonely and heartbroken this time. Of course there would be pain to work through, but you are not the same person you were back then and now you are beginning to see things as they really are.
There is a little spark of resilience, of "no, I do not deserve to live like this" that occasionally comes through in your posts. I hope it keeps growing. It will help you.
That anger you've started to feel - that entirely justified anger you are feeling - will help you too. Anger is protective, it tells us something is happening that is wrong, and it gives us the impetus to change it. Anger is only a bad thing when we use it as an excuse to hurt others or allow it to fester without doing anything to change the situation.
You will find you continue to swing between the growing clarity that this is abuse, and feeling attached to him or guilty for telling us what he's like or for daring to contemplate the idea he is abusive. He has done this to you. It's part of how he has kept control of you for so long.
I remembered as I was reading your posts how very low I had the bar set when I was at this stage. All he had to do was walk into the room, refrain from yelling at me, say the word "hello" in a neutral, non aggressive voice then walk back out the room and resume ignoring me - and I would feel like I was a terrible person for contemplating leaving, and oh of course he wasn't really abusive (how horrible was I for even thinking such a thing) because he had just managed to say a single word to me without being vile, as if I was an actual human.
And I would hold that up to myself as proof he wasn't abusive, because for that single instant he wasn't doing anything terrible.
I am glad that you confided in your sister and that she responded the way she did. I was afraid to tell people, and felt like I would be imposing. Except everyone I told was distraught to learn what had been going on and how bad things had been for me. They felt guilty for not having realised. They told me if they'd known they'd have tried to help me leave.
It was only when I picked the least bad example I could think of to tell someone, and they recoiled in shock then started crying, that it sunk in for me how badly he had distorted my perception of what was normal and acceptable.
Have you given any more thought to the Freedom Programme? I really truly think it would help you sort through this, and be able to see what is happening without all the self doubt he has planted. Freedom will never tell you that you have to leave, so attending it doesn't mean you have decided to leave. You can view it as a quest for knowledge and nothing more if you want to.