Well I think when you start hearing them talk about you, you should confront them, stand up to them. Find out why they choose to treat you like this. If you absolutely feel that you aren't able to do that, then you should probably avoid these people (but I still see that as a last resort). I wouldn't normally tell you to just not go altogether either but if most of them are truly picking on you, and there is no one nice you could spend time with while you're there, then I think you should stay away and instead be around others who appreciate you because you shouldn't be made to feel this way.