My older sister has been an issue in our family for years (most of my life, 29 yrs). She was diagnosed with bipolar in her teens and has been on and off her medication. When she's on it, there are no fights, no tension, and I feel closer than ever to her. But when she feels she's better, she thinks "I dont need it anymore " so she stops and becomes manipulative and abusive mentally to me and my mom in particular. Mostly because mom took her to the doctors when I found her cutting when I was 6 (She tells us all the time). Now I have bought a house for my parents, my fiance and I to live in and she is moving in with my cousin. She was supposed to help my mom (70 with arthritis in her back) a week before to move and toss old furniture and trash from the place they were renting together. Two days before they have to be out, she told my mom to figure it out herself and left her there without doing anything to help (I would have helped much more but complications at work would not allow me to take days off). My other siblings and I were able to help after work so my parents wouldn't loose their deposit. My fiance is very upset with her and wants to disinvite her to our wedding. I do understand and agree to a certain extent. I don't want her there out of fear she will make a scene which I don't put past her to do. But I do want her son there because we are close, but she would make him feel guilty going without her. So do I invite her and risk her making a scene or do I disinvite her and risk my nephew not coming and having issues with his mom?