This definitely seems like a serious issue. Have you tried speaking to your friend about it? If you are having trouble at school it could be due to false rumours or the like. If someone wants to lie to you like that then they may not really be a close friend, more like an aquaintance. Some people are unfortunately excluded from social bubbles for really silly reasons because other humans are cruel. I really understand what you're going through, my best response would be to try talking and if that doesn't work, try different areas of friendship. I personally felt that lack of connection, especially in my mid and early teens, so I tried discord instead. Ended up with a bunch of people who I could chat to and relate to without feeling left out or uncomfortable, however if you do this you need to be careful. Remember not to reveal personal information or the like to anyone. Sometimes just talking about the issue can help. I hope you feel better before the year is up, it may take time but remember: You're worth it!
If they’re gonna mess you around like that I’d say stuff them. Why let them use and disregard you? Don’t let anyone drag you down, rumours and hypocrisy are for boring people imo. If you need to chat I’m always here and I’m sure so are the majority of tsr. Good luck, seriously.