Breaking up is hard to do. But you can do it.

Do you have to go to the party? Just stay home. You can say you're sick, or even say, "I just broke up with my boyfriend, and I'm not in the mood." As for people staring, why would they? I'm not saying people don't point and stare sometimes, but in general, people don't go to parties and pick a person out and stare at him or her. Most people will be chatting within their own little circles, perhaps moving around to greet and chat with others. If they stare at you, go over to them and ask them why. If it's an insult, tell them to F*** off and walk away.