Please help I am giving up on life.?

Ok so i am 13, i am in 7th grade. my family are all about saving money and havent bought me anything since i was 11. my sister and i are constantly fighting. school is a whole 'nother story. so i went this guy's bday party (my ex boyfriend). i moved away last year but came back. there is this girl who is my supposid friend, and without even talking to me, she just started dating him. I found this out when i came back, and i got invited to his pool party cuz my parents and his parents are family friends. I saw them talk and then hug and get out of the pool and hold hands and i started crying. but anyway i got depressed and now everyone taunts me and calls me el-depresso. I am running away, so dont try to persuade me. please tell me HOW to run away.