Why am I such a failure, what do I do wrong?

I used to be so outgoing and talented. My grades were good and I had a lot of friends. As soon as highschool hit, it's like I became a completely different person. Okay well I lost my best friend after 7 years, she's this huge pothead and doesn't go anywhere without her friend, my mom left and didn't talk to us for a year, then I ended up moving in with her when me and my dad got into this huge fight. She had a boyfriend and we started to really get along going into the end of my freshman year. With them, I pulled all of my failing grades up to A's and B's... and I became more happy and outgoing again. But during the summer I got really depressed again, and switched to a new highschool going into my sopre year. I've been in school for two months now at this new school and I have no friends. None. One girl has even spread rumors to other guys that I want to sleep with them when it isn't true... so now people think i'm easy and go out of their way to avoid me. So my day seemed a little brighter today because I was actually going to do something during the weekend... my grades aren't good, i'm just a sad person. So I asked my mom if I could go to a party with my old best friend who's now just a friend, and she said she didn't know. So I asked to hang out with my old friend that moved over to chicago. (I live in wisconsin now.) and she said yeah, that she could come over saturday, and I had planned for my old best friend to hang out with me at a party friday... so I asked about that again and she said pick one friend. (haven't done anything in literally a month with anyone. I only do stuff with family.) so I started to get mad and said I never do anything and family doesn't count as an activity. So my moms boyfriend gets home and says there's this tutor for math afterschool to help with my math grade. I said I would p on it because it's one hour and 20 minutes long... so he got like furious with me and called me a brat. He said I needed to grow up, to go pout, and said i'm pretty much a failure of a person. So I threw down my pen and said I knew he thought those things of me a couple months before and he's like, well good, i'm saying them now. And I was like, good job for finally saying it to my face. and I went downstaires, called my dad, and now he's picking me up later and i'm never coming back here again. I know you guys are going to call me a brat and say he's right, but I need help. I have no one to talk to, I feel like I missed out on my mom, she doesn't even like me, she changes for all of her boyfriends and I just want her to care about me. All I did was tell my moms boyfriend that I was studying for the tests and getting bad grades, but turning in every homework ignment and getting A's, and he goes and explodes on me. He's never yelled at me before and now I feel like a jack for yelling back. It's so disrespectful and not like me. Can someone just calm me down and tell me what I should do? I feel like I ruined out good friendship. I can never look at him the same way again. I just need a life change.