I refuse to attend my sister's wedding because I once dated her fiance and I can't face his parents
Is there another reason that you don't want to see him?
I had an affair with him
I still think that you should try to go. I think that weddings are one of those things that are important for you to show up at.
I don't care. I'll just make them break their engagement by telling her sister.
Thats pretty harsh. While you might want to tell your sister about who they're marrying just be aware that they might already know about their fiance's past.