So Torn

My wedding is at the beginning of July and I haven't asked anyone to be in our wedding yet. My fiance has already asked all of his groomsmen. The reason I haven't asked is due to a fall out with my sister right around Thanksgiving. She said some horrible things to me and the rest of our family because we don't support her relationship with her husband. He has gotten her involved with drugs that have basically changed her into a completely different person. Since the fall out she hasn't spoken to any of us, but this isn't the first time this has happened. She has sworn before she would never speak to us again, but then turns around and begs for our help to watch her son, give her money, etc. However, this is the longest she has gone without communicating with any of us. Prior to the fall out, I was planning on asking her and the rest of my girls to be bridesmaids. I am really torn on what to do. I would love for my sister to be in my wedding, but sine she isn't currently speaking with us I don't see that happening. There is a chance she could change her mind between now and the wedding. I feel like one of two things could happen. 1. My sister never talks to us again or 2. My sister changes her mind, reaches out to us, and then gets angry at me when she finds out I didn't ask her to be a bridesmaids. I am not sure what to do. Would it be bad that if she does talk to us again then to ask her to be a bridesmaid or should I completely forget about her being a bridesmaid? Any advice would be appreciated.