Hi soooootired. I know you miss your grandkids. Unless your daughter has had some kind of awakening or mental growth she maybe the same vile person that you had to get distance from so you could feel some kind of peace in your life.
Recently I let my bipolar/borderline sister in law back into my life after 20 years of not talking to her. I thought maybe she had matured or got better but H no. My husband, her brother warned me to not do it. She is the same arrow throwing vile person as before. Wish I had not opened that bag of worms. How could I forgive years of grief from her and think she would be better or have grown spiritually mature? Now I have more grief because of her. It will be another 20 years before I can let her in again. This last bout with her caused me to go into depression and some of my depression is aimed at myself for being so stupid to think a person like that could act decent and not cause so much turmoil.
My 39 year old daughter is borderline/bipolar, I have gone months without talking to her. When I went 3 months and not said one word to her it make her grow up a bit. She still is very difficult to deal with but not as belligerent as in the past. Her constant lying is very hard to deal with but the trade off is the belligerence is better. My daughter knows I have the strength to get space when I need it.
I hope you do not feel guilty for having your peace. I hope you listen hard to your gut and only follow what your heart tells you. Of course having a daughter back in your life in a healthy relationship is a wonderful idea but if it is nothing but horrible and abuse I hope you do not open that huge bag of worms.
Good luck with your major decision.