All My Friends Hate Me?

[XoxoX]

I have a group of 6 friends at school and i feel like they all hate me. we used to be really close last year but now i feel like they have all gone off me. they are constantly looking to argue with me and are trying to find any excuse to get rid of me. They also always leave me out of plans, they tell me theyre all busy with family stuff but then i see pictures on facebook of them hanging out together and having sleepovers with eachother. Also, even if they do make plans they often just leave me hanging and wont contact me and meet up with eachother instead. I feel like they only use me because they know that id do anything for them because its in my nature to be giving, and i expect nothing back but i constantly feel worthless and depressed like im not even worth the 2 seconds it takes to reply to a text and that im a burden to all of them. I want to leave them because i feel like they would be much happier without me there but its hard because ive known these girls all through high school and its senior year so i only have to feel this way for 6 more months untill college. I dont know what to do though because its making me so unhappy, i havegenuinely considered self harming because i feel so bad about myself and if i try to tell them how i feel they call me attention seeking. i need some advice