Are you comfortable sharing why you avoid your sister? And have you discussed it with your sister? I'm wondering if she knows the anxiety you feel.

My mom is a huge anxiety source for me, so I am familiar with avoiding someone. Moving 80 miles from her several years ago helped immensely! Although this isn't a viable solution all the time. Still she continued to email, call, etc. It got to the point where I just told her openly and honestly, 'Mom, this is how I feel and I am not going to to continue to have contact with you.' Months went by with no contact and now I have very limited contact with her. She rarely ever calls and only emails occasionally.