it was leave, or die where I was
Hobgoblin this so resonated for me (actually so has a lot else of what you have said). I'm about fifteen years further away "out" of things than you are, but I can still remember that moment of realising that I seriously would die, if I didn't get out. Not because he would kill me but because I would end up acting on the suicidal thoughts that by then were my internal wallpaper. So much so that I'd almost stopped noticing them, if that makes sense? I was almost sleepwalking into it, until that jolt.
I just felt so entirely emptied of "self". You know that Shon Faye "enjoy your erasure" quote? That's what happened to me (minus the enjoying bit, obviously). Over the dozen or so years my ex and I were together every single bit of my identity got sort of leached away. You can't be allowed to be attractive because his legs must be "better" than yours. You can't be allowed to have clothes you like because he wants the same, and if they don't come in his size you can't have them. And if you (in the early days) buy them anyway then he'll wear them which tears/stretches/ruins them. You can't have women friends because if you come home and say you didn't spend the whole time talking about clothes and make up then you're a failure as a woman. On and on, drip and drip, boil frog, boil.
I can still remember one night (and this was some years before I did finally get out) sitting crying for hours in the shower because I was there naked, and if was naked then I was nothing because "woman" was all about makeup and clothes and everything except bodies, especially not my body.
I am so lucky: we didn't have children, so when I finally ran I was able to run and run and run.
I also competely understand what you have said about not being able to talk about it. This is the most I have said about it in nearly two decades and I only feel able to do it in a doubly anonymous way (in that I have changed my mumsnet username for this post). It's not "shame" exactly (though I completely understand why you have used that word, it's about the cloest word there is). But talking about it brings back that terrified emptied out person that I was. (Still am in many ways).
Someone earlier in the thread asked if they could quote/use, anonymously, things people say here for a speech/article; that is OK by me.