M.P.
Have you considered the possibility that she also has Bi-polar disorder? She certainly has symptoms that would indicate that possibility. She would have a greater chance of being bi-polar than the average person because you're bi-polar.
My daughter acted in similar ways after I'd sacrificed to help her start adult life. She became pregnant at 19 and was not at all prepared to handle being a mother. She was moody and difficult to get along with and no matter what happened it was my fault. That's a bi-polar characteristic. I suggest that you do some reading for family members of one who is bi-polar. Even if she's not bi-polar you will find many suggestions on how to be with your daughter.
The hardest lesson for me was how to stop giving so much of myself to help her. When I finally let her suffer the consequences of her decisions and actions, to include being verbally abusive to me she learned how to behave appropriately. When someone berates us the healthy thing to do is to leave. No one else, but her mother, would stick around to listen to her scream, yell, and blame. You have to tell her that anytime she is rude you will walk out the door.
I learned rather quickly after telling her that i would leave, that I had to immediately leave or else I would get sucked into defending myself. I cried every time as I walked to my car. Doing this was so painful. I wanted her love and appreciation for what I'd done for her and leaving felt counter productive to me. I felt that I had to convince her that I loved her. But it worked! Hallelujah! In just a few months she and I worked out a way to relate with each other that has been satisfactory to both of us. One of us will tell the other when we realize that we are approaching feeling angry and sometimes we just stop talking about that subject or sometimes one or the other of us leaves while we're still on good terms. It did take several months to reach this space in which both of us feel loved and appreciated.
It"s seems odd that she also felt reject by me when I was staying and fighting with her. At the same time she felt comfortable with our fighting because she grew up in a family that fights to show their love. (She started life with me at 7 as a foster child) Perhaps, as a social worker, you have insight into my situation. It's much easier to see something in someone else's behavior than in our own.
Because of some of the similarities in our relationships with our daughters I'd also like to suggest that some of this happening because of boundary issues. I suggest you are doing too much for her which causes her to feel too much like a child. My daughter specifically told me that I treated her like a child and that she needed a friend and not a mother. Of course, she wanted me to continue taking care of her but to not have ideas of my own about what she needed. Because I took care of her baby while she worked I did much of the housework. She didn't even recognize that I was doing that and would be angry if the dishes weren't done when she came home. She truly did not appreciate what I was doing for her until I stopped doing it.
I think you've done more than enough to help her: more than I was ever able to do for my daughter and I did way too much for her. It's time for you to let her manage her own life and deal with the consequences of her choices. Be as sympathetic as she'll allow but back way off emotionally. And do not get sucked back in when she cries on your shoulder. Yes, she wants your help but she cannot appreciate it.
She has told you what she wants from you; to be a grandmother to her daughter but do not make comments, suggestions, or engage in much conversation with her. Respect her request and stick with it even if she changes her mind because she will change her mind right back again once she's hooked you.
There is a book entitled Stop Walking on Eggshells that helped me to better understand what was happening between my daughter and myself. I read it years ago and didn't understand what it was saying but in the last 5 years I finally do understand that my daughter and I did not have a healthy boundary between us. It was up to me to make that boundary.
I also was helped by counseling and suggest that if you're not still in counseling that you go back to it. This is an issue between the two of you and each of you have issues contributing to it. You can foster change by changing yourself. You can eventually have a good relationship with your daughter but first you have to find a way to be kind to yourself. You cannot make up for all those difficult years. They happened and they do influence today. However, you can only deal with today after you make peace with the past. I wish you success in this new journey.