I got invited to a party I dunno if I should go...

I got invited to a x mas party that will be coming up. I was infatuated with my friends sister who is throwing the party. She will definitely be there.I know she doesn’t like me like that. I have not thought about her in about 5–6 but still dunno if its a good idea for me to go. I just don’t want to have a relapse and be miserable. But going to the party could also end up being a good thing.. I need opinions