Mate's mean sister ruined my birthday so I've cut both out

There's a woman in my friendship group who I've known since school and she was the classic mean girl - pretty, popular but not a very nice person a lot of the time.

- Dear Coleen

I give her a wide berth these days, but I am good friends with her sister, which I suspect she hates.

Recently, I had a party for my birthday and she was there - I felt I had to invite her as everyone else was coming, so it would have been weird to leave her out. I'm not a mean girl!

However, true to form, she spent the whole evening either ignoring me or making barbed comments dressed up as humour. Well, it wasn't funny, especially on my birthday.