Hi bluebicycle. I absolutely understand your concerns and pain about your sister's exploitation of your mother. My family has had similar concerns about "friends" of my father exploiting him, during times of weakness. Have you had a long talk with your mother about these concerns? Fighting your sister about the issue may be a losing battle. My siblings and I have found that to be the case with my father's exploitation. I can't even count how many times my brother has confronted my father's exploiters, to no avail. In the end, it's up to my father not to be exploited. In the case of your mother, I'm assuming she is of sound mind and perfectly capable of making her own decisions. My siblings and I have questioned how capable our father is, but it's difficult to reach a point when you take away someone's freedom to choose.

Forgive me for forgetting if you live with your mother or not. If you do, I suppose totally avoiding your sister may be difficult. If you don't have to come in contact with your sister, you can choose to shut her out. I know it sounds horrible, but if it is for your own best interest (psychologically, etc.) it may be a good choice. My husband and his eldest sister have basically ended their relationship, but it is not so complex as what you are facing. Their parents passed away, and his eldest sister lives very far from us. As an aside, his eldest sister has bipolar disorder, which she refuses to treat. Hubby's eldest brother doesn't talk to her either. Everyone else complains about her.It's sad!