my sister has anger issues, and it has escalated to her walloping me round the head. She used to do this to her husband, and to me when we were teenagers. This is only the second time shes' done it since we are adults. I feel i have to draw a line under it now and have refused to see her except with other adults present (she hit me with my young children looking on). She is treating the incident as if it were a tiff. I want to help her, but I don't want to leave myself vulnerable again. Is it unnecessarily cruel to keep her at arms length this way?