My self esteem is seriously awful at the moment..how can i feel good about myself?

[VivaGlam]

okay so i mean since school started in september my confidence has gone waaaay down. like i was never confident but now..its just awful. See the begining of the year was good, i was secretly with this guy over the summer and when school started and like that made me feel good. but then like it came out in the school alll our friends and it ended and he got girlfriends and well baisically he is the biggest player in the year and he used me. but when people found out he told one of his friends that he didnt want people to know because he was afraid they would slag him. but then at christmas he text me again and i stupidly did stuff and then like he got a girlfriend like a week later. So really my confidence has just continuously been going down and now i just really want to come home and cry every day.like my year is awful, theres so many groups and im not the popular one so all the abuse in class is just towards me..and i do find im probly the most unliked girl in the year. like everyone gives me filthies even people i dont know..i could be with all my friends and get eveils of people.and a few months ago stuff happened with my cousin who i was really close to and that upset me a lot and now i feel like im loosing my best friend to this other girl that we have only been proper friends with this year who i dont like. its not like i dont take care of myself..i do everything beauty related, make up hair clothes, i do take carer of my appearence and its important to me..and i wouldnt say im ugly..just not like pretty..?i need to feel better about myself..but i dont know how? im 15