If your boyf is going then you should still go too otherwise these girls have got what they wanted. They don't like you for whatever reason that's their bloody problem, that shouldn't stop you going! Stick to your boyf like glue, but if you see any other people on their own then go over and try to chat to them, chances are they are feeling as left out as you and you never know you may make a new friend who you can hang around with at these parties in the future.
If these girls keep giving you dirty looks, look them up and down and just laugh at them and then get back to enjoying yourself. They're pathetic girls who clearly haven't grown up from being bullies at school to everyone who didn't fit into their gang! Bet you'll find there's one in the group (if not more) who only goes along with it cos their too scared to speak out!
You go girl and snub the girlie bullies! :o)
......and more importantly have fun!