I guess I just need a place to vent to people who don't know me. It's a long story, and I don't even care if I don't get any replies, but I just need to let some steam off.

I'm currently a senior in high school, and I live in Alaska. I don't know if that's relevant to anything, but whatever. Last year, before my 17th birthday, my cat died. He was everything to me, and I thought losing him would be the hardest storm of the year. Unfortunately, I was wrong. A month later, my dad deployed on a 7 month tour. Barely two months into his deployment, his marriage with my mom began to falter. Soon enough, in about another month and a half, mom and I find out that dad was having an affair. My mom falls into a deep depression, stops eating, and basically starts self-harming in unconventional ways (mostly through self-starvation and over-exercise.) For the next three to four months of the deployment, I had to take care of my mom and basically become a counselor for her. I was still only 17. Soon enough, my grades start slipping. I began lashing out at teachers. I started 'running away' from home. I would just get in the car and drive for hours, waiting until late at night or early in the morning to come home, just so I could avoid having to deal with mom in her state. I know, it's awful, and I should have been there for her as much as I could, but I just couldn't. Kids shouldn't have to be there for their parents like that. Moms are supposed to be the heroes, not the kids.
I told no one what was happening, save for one person. I would often go to his house just to get away. Even though it was nice to let one person know, it didn't take away from the pain of it all. My grades started slipping even more, and I basically gave up on school in general. I hardly tried, I just didn't have it in me. I took care of my animals, and that was it. Fast-forward to summer, and dad gets back. I have to act as a conduit between him and mom, because he wouldn't talk to her. When they finally did start talking, I would just leave the house. I would be home just long enough to turn on/off any heating equipment or lights for the lizards, and then I would leave. Mom hit absolute rock-bottom, and began having to go to the hospital for anxiety. She finally decided she couldn't stay in the state, so she packed up her bags and moved to Montana to live with her dad. I was relieved, but only for a few days.
School starts up again, and I'm a senior. Right off the bat, I can't stay focused or motivated during school, or after school. It didn't take long for my grades to start slipping. I eventually got to the point where I just wouldn't show up to school. Only two teachers noticed, but only one asked if everything was alright. I lied, because I felt that it wasn't a burden others needed to carry. Soon, my counselor noticed, but she wasn't any help.
It's almost the end of the semester, and my AP Lit teacher doesn't want me to fail, so she holds a conference with my dad and I. While dad is there, I didn't say much, I just agreed to whatever my teacher said I could do to make up points. Once he leaves, I just lose all composure. I don't think I've ever cried so hard in my life. I just pour my heart out to my teacher, and tell her everything that's happened in the past year. I confessed to her that I felt I would be better off dead. I'm not suicidal, but sometimes, I still feel that way.
I manage to get my grades up just before the semester end, and I was so relieved when winter break arrived. Mom came up for Christmas, and it was good to be with her again, but still so difficult. The rest of winter break was actually really great, I felt like things were finally looking up; I had a boyfriend and generally felt happy for the first time in a while. He doesn't know much of what's happened, and I likely won't tell him for a while. I feel it's not something he needs to worry about. Regardless, I feel like my last semester is going to be great, I'm going to study often and finish strong.
I don't think that's going to happen now. It's almost the end of the 3rd quarter, and I'm failing one class and have a D and two Cs in my other classes. I just now signed up to take my SAT/ACT, and I'm so far behind. I don't understand what's going on in my government class, I feel like I'm barely above the surface. My whole life is in shambles, and I'm just trapped in this dark hole of depression that I'm too afraid to admit to. It's easy to type out to strangers, but I couldn't possibly tell anyone this in person. I feel like I'm just a burden to everyone around me, and I'm just a f*** up. My relationship with my boyfriend is great, but aside from that, I feel like a failure who's never going to be as great as her brother, who's never going to make it to college, and who's never going to amount to anything. I just want to be a kid again.

This isn't even the full story, I'm leaving out so many details. Like the fact that my dad asked me to console my mother when she tried to kill herself. She literally had the gun in her hand. I don't know if anyone here knows the feeling you get when you realise that you're not enough to keep your own mom from taking her life, but I would never wish it on anyone.

I'm not the strong person everyone thinks I am. A few people know bits and pieces, but I wish they just knew how tired I am. I can't keep my head above the water anymore, I just can't do it. I'm so afraid of what's going to happen, of where I'm going to end up. It's like being trapped in a room with no doors or windows. I feel like there's no way out.

Sorry for the wall of text, but I just needed to let it out.