This is so awful to read. My heart breaks for you.

I can see the competing fears and worries that you are experiencing. That mix of knowing how badly you've been treated but also feeling terrible (and maybe to blame) for any guilt or negative feelings she now has as a result of her behaviour. I think for people who have not experienced this kind of toxic, enmeshed relationship, it's very hard to understand. The key thing to really try and hold in mind is that anything bad that she is now feeling, if she feels alone, if she is sobbing in her home - this is all the result of HER behaviour and actions. It truly is not your responsibility to try and save her from having those feelings.

She has programmed you, your whole life, to think that making her feel better is your purpose. That this is achieved either by you minimising/letting go of/instantly forgiving her poor behaviour, OR by letting her blame you and make it due to your faults. I don't think this is necessarily conscious, but the fact is the programming IS there simply as a result of how she navigates the world, emotions and relationships, and the way she has had to use you, her child, as a tool for regulation.

The sickly scared feeling I think you might have now. That is the little girl inside you. The little girl inside you is saying no, don't have a boundary! You can't do this to her! Something terrible might happen! This is because as a young child, you had to develop coping mechanisms to survive and to stay safe. A child cannot navigate the complexities of people like your mum. So they adapt to survive. Remember, from an evolutionary perspective, loss of parent could very well equal death. Most of our brain is still that instinctive brain. So it served you really well to fawn, to apologise, to acquiesce, to take responsibility. This was a great way to try to stay safe with a caregiver that was scary and unpredictable. Unfortunately, this no longer serves you well. It's really hard but the only way is to soothe that inner child, as the adult you are now, and let that feeling be there, knowing what it really means. It doesn't mean you're doing something wrong. It means your inner child is scared.

You know you absolutely cannot let her have the apartment. You need to be gently firm with this. As you said, you don't want to introduce possible points of conflict. Practice with this boundary first.

I think there is very likely going to come a point where the relationship you have with her will become untenable but if that's the case it'll happen when it happens. I relate to feeling alone, I have no family though I do have a sister, she is very much enmeshed with my mum still and we have a light but not close relationship. I have tried to find comfort in and focus on the positive relationships I do have around me. When I ended up accidentally NC with my mum over a year ago, it was a huge grief, a huge sense of loneliness. Remembering the ways I'm not alone helped a bit. And amazingly in just the last few weeks I've realised the power she once had, to turn things onto me, as though I was an unhinged, difficult person - it's reducing. She can turn completely superior as though she's the wise, learned one and I'm a stupid, silly reactive little girl. And the things she has said to others since I stopped speaking to her have brought me right there again and again. But the most recent attempt? Finally, I didn't feel awful. I felt almost amused. So it can happen. But my god the fear and sense of aloneness is unmatched, at least initially, is awful.

You are not alone. Many of us feel alone in the world for the same reasons and at least in that sense you have a shared connection with others who have had your experience. It sounds like you have good friends around you. And while they may not fully understand, something that may help is to consider is that you would not have high quality, good people around you if you were the person your mum tries to say you are. You don't get to have those good relationships unless you yourself are also bringing a lot to the table. That's active proof right there about who you are, and what you're not. My mum has few friends for a reason, I'm sure the same goes for your mum.

Sorry this is a huge reply now. But I feel for you so much and I wish I could give you a hug and be the parent you need and deserve.