Hey sorry to hear this. I think what it maybe is just simply that you - and they - have moved on. I think many people find themselves in simular situations. Maybe what you should do during the next holiday is maybe arrange to meet up and do fun things that you don't normally have time to do with any good new friends that you have made at uni. Maybe go visit them, and invite them to your house.
I don't want to add to your worries, but I can't imagine the situation getting better with time - unless of course you take drastic action with your friends at home. Perhaps one thing to consider, is do you keep in touch with your friends at home, whilst you are away at uni? Because if you don't, then maybe they'll see it as you left, didn't bother to keep in touch, and therefore aren't interested.
Me and my best mate are at uni in different cities and I get really annoyed because he doesn't make half as much effort to keep in touch during term time (we do keep in touch, and are getting better at it), but yet when we're both back in the same city, he expects things to just carry on and pick up where they left off. I guess it's difficult for us all to find the correct balance, given the work, time, distance and other pressures that us students have to cope with.... why can't life be nice and simple, I ask?