Work Life vs Personal Life

So I met two of my sister's at work many years ago. Since then we have all grown and (well most of us) have matured. Both of them moved on to other jobs that were specifically related to their fields. I stayed and moved up in the company. It is not my field of choice, however it is a deffinite back up option. I know that if I want to move up further I can. So for the last couple of years, all four of us have had completely separate and distinct work lives. Obviously there has been some overlap, but for the most part they are separate. When my sister C left, she had nothing but negative things to say about the company. Well she now claims that her current job is not paying enough so she took on a couple days at my company. As a side note, it is fairly well known that C and I have not been getting along all that well lately either. I saw her there today (we were both working) and I was astounded at the anger that I felt. Because we all have pretty well the same group of friend's, this company was my territory. I found it totally annoying to hear her for the last hour of my shift. I see her often enough as it is, just fucking let me do my job without hearing her damn voice too!!!!!