I have a sister that fits into that description. After years of listening to her go on and on about how badly she was treated, and then watching her manipulate everyone, including her own kids, I knew I had to step back. I wonder why you feel you have the need to rescue her and take on her issues by supporting her. I think at some point everyone is accountable to themselves, and sometimes we are enabling them to not see things as they really are. I made strong boundaries with my sister and no longer feel responsible for her, the best thing I could have ever done. She was toxic to me.