I have someone that wants to come to my New Year's party but I'm not going to invite them.
Is it someone specific?
Yes, one of my friends recently split with his gf
I don't see why it would be a problem to have him come to the New Year's party. Him breaking up with his girlfriend has nothing to do with you.
It's a dick move, man.
I get you may not agree with him breaking up with his girlfriend, but it was his decision. I will try to focus on having a good time if her friend and I think that would allow you both to have a good time.