So basically a couple of years ago my uncle cheated on my aunt. (They're divorced now it's been a whole thing. We still see my uncle but it's not the same.) He  is now romantically involved with this same woman and brings her to all of our family gatherings etc. My family and I aren't huge fans of her for multiple reasons (attitude, the fact that she got inbetween my uncle and aunt etc...). Basically no one in my family likes her or respects my uncle. 

Cut to this year.  My SO and I are sending out Christmas cards. As we go through our list my uncle comes up. We debate about whether or not to include her. I consult my parents and they basically say no we shouldn't. My SO is having second thoughts and says it looks bad if we don't.  While I see where my SO is coming from, I still agree with my family. My SO is on the side that we should let the past go and move on with what we have now. My SO has a different point of view because there have been divorces in that family but nothing that involved cheating like this. 

I guess my question is; am I an asshole if myself and my family continue to not respect my uncle's decision? Or should we just suck it up and include her on the Christmas card?