About 4 years ago, I did something really, really mean to someone. I want to apologize because I think they deserve the apology. However, it was an ex-boyfriend, and he's married now (has been for about 2 years, we've always been friends on FB, but have not spoken). I also am in a relationship, if it matters.
I don't want to cause any type of problems by sending him a message or anything, but I do think it's necessary to apologize. I would send a brief message and just say sorry, cause it was honestly quite fucked up.