Friend trouble Please help my tears run non stop :(?

Ok i have been an outcast since i was in pre-k i had no friend's until 9th grade. It is this particular girl i use to be BFF with like seriously a few times before she ditched me but i excepted that because everyone wants to be her friend an hates me. She promised me would never do it Again once she almost did her friends ( who everybody loves) invited her 2 go to the pizza place she said yes but before that she said yes to me but then she realized she wanted to hang with me so ditched them. So i had a sleep over and invited everybody but then she started talking about them and it got out they hated her so she hung with me evens more but then we started to hang with this other girl who hated me last year but started to like me. So we all be came best friends like the real deal but then she ditched us for the other girls so then it was me and the girl who hated me last year me and her became even closer. The problem is she is in love with that girl who ditched us (friend like) i understand because everybody is obsessed with her the girl who ditched us became bff's with some other girl who everybody love's also and there names orr even the same. But what happened was my only friend the girl who use to hate me stop talking to em a couple of days ago just like ignoring me and talking to those to. Now i am all alone no one to talk to and all i do is cry and cry and cry and when it rains i go to sit in it and sometimes even have suicidal thought but im scared to attempt i am diagnosed with depression cause i am ridiculously lonely and have no socialization what should i do ?