>>3 Yeah I get it. It's hard to stop caring about your friends even if they don't care about you. Try involving yourself in clubs/activities when you go back to school, so you can find people interested in the same things as you.
I have no other ideas of how you could find different friends, because it's kind of hard to just APPROACH someone without it being weird, but if you notice someone in class and they seem nice and you're bold enough to do it, try asking them if they want to hang out. =/ It's a longshot, but try if you can.
I wish you best of luck =)