You are right, the physical distance is a blessing (as is caller display!).
Looking back, I was an emotional wreck when I was in my late teens. Even after I left home - when i was 21 - I still took years to begin to calm down enough to be able to see the wood for the trees.
The day I stopped Mum hitting me was an epiphany and the day she apologised was a blessed relief.
I don't know if I said it upthread or not, but my sister and I feel out a couple of years ago because Mum had me in her sights at that time. She was running some nasty whispering campaign against me - I can't remember what it was about, just that it was my turn again. I knew my sister had heard what she'd be saying and I happened to be visiting my sister the following week. I wanted to talk about it. Really I wanted my sister to say she knew it was not true what Mum was saying.
She refused to speak to me about it (maybe some of you will think its understandable). I felt like she had witnessed me being attacked and had refused to help me. I was asking very little, only that she say she knew it was an unfounded lie, but she wouldn't even do that for me. Since then, I've been keeping my distance from her anyway, and its not like she was making any effort to call me, so we rarely speak.
I guess she did not know that things had improved between me and Mum until she heard about the planned weekend away. So, she called me up and asked if she could come to. Then she wrecked it.
And then she looked very hurt when i (calmly) told her that I nearly went NC with the family many times over the last three decades and I wasn't sure why I hadn't as it would have made sense. I told her that she either dropped the "blacksheep is the wild one" routine forever, starting now, or she'd cease to be my sister. I said I didn't want to lose her, but I am more unwilling to dragged back into living that lie again. So, its her choice.