Mostly venting but also asking for advice.

Taylor
My step sister and I have always had a rocky relationship. Our personalities just don't mix well. At one point we both tried, and with the exception of a few blow ups are fairly civil towards one another. It's a complicated relationship, because I loved her deeply but probably more so out of love for her father (my stepdad) than actual love for her. Who knows. Our best point was a few years ago, we were living in the same town again, I was doing my thing and she had just gotten a job as a live in nanny in the area... Then she became "best friends" with the wife but had an affair with the husband. I couldn't believe it, I knew she admired the guy just based on how highly she spoke of him, but at the time she was only 19 and he was in his mid forties! I thought MAYBE she just liked him as a father figure. Anyway, I thanked God my husband and I moved across state because even though she didn't hurt me directly I couldn't help but hurt for the wife. The guy turned out to be a complete (insert word of choice), left his wife but of course cheated on my sister, he never has money for his kids' food (he's a weekend dad now) but always reeks of cigarettes. My sister is still with him, &often she asks for groceries or money. (I made it clear I can't help her, hubby and I have our own family to feed. I point her in the direction of places in her area that can help her). I haven't given her much thought in the last year or so. Then mom said that she and step dad had dinner with step sister and jerk face for the fist time. Now I'm already preparing myself for the holidays and the possibility of seeing the two. I don't want to be or sound so judgmental but I just have such a hard time wanting her back in my life and especially in my family's life (hubby, baby, and I). I guess because her, um, ordeal happened the same time hubby and I got married and found out we were pregnant, the whole thing was WAY too close to home for me. She has actually done some pretty awful stuff to me in our past, she spread false rumors about me (she told whoever would listen that I was "the household slut"), faked multiple miscarriages to try to gain sympathy from myself and others... But I was pretty quick to forgive those things when they happened. I've only ever been with my husband, we're high school sweethearts, so as long as he knew I'm faithful I didn't care what lie she told or whom to. & figured if she wanted to fake a miscarriage every year it wasn't my business.. What I struggle with now: her relationship with this scumbag technically isn't my business either, sometimes I can't help but to think they actually deserve each other. Her affair didn't involve me in any way, and even though I've never met the (ex)wife I can't help but to feel pain and anger on her behalf. My step sister may not even show up for the holidays so I may be thinking too much for nothing, but how would you guys feel or handle this? Would you avoid her entirely if she and the guy showed up for the family get togethers? Or am I being too judgmental? My step dad obviously wasn't happy with his daughter's choices but decided his relationship with her is more important than what he's feeling. I just don't know if I want to do the same. Our relationship as stepsisters was pretty crappy anyway.