I'm sorry. My parents divorced when I was older (out of college, married) but it still sucked.
Don't feel like you have to be one parent's support network. My mom would frequently talk shit about my dad till I had to tell her that just because they were divorcing, it did not change the fact that he was my dad and would always be my dad. If she needed to vent about that, she had her own family members and friends to do that with. If she couldn't respect that, I would end the phone call. I did actually end up hanging up on her once, after that she didn't bring him up again for years. Your siblings should do the same thing, and lean on each other if you can.
You're going to college - as soon as you're able to, get in touch with the student mental health services. I found counseling to be very helpful because I felt like I couldn't see the forest for the trees and they helped cut through that to the actual issues. In your case, you're at a major transitional point in your life and this is rocking your foundation so I'd say it's even more important to seek counseling.
Do your parents have the living situation sorted out yet? That will affect how you figure out how to spend time with each parent. In my case, I had my own house so I ended up hosting a lot more and didn't go back to my home town for something like two years just because it was So Awkward (plus it saved me the drive, which I didn't mind since at the time I had less free time than they did). Usually we always did holidays with my mom's family, so the past few years we've driven down to stay with my dad and then gone from his house to my mom's family for Thanksgiving or Christmas.
I feel like I'm forgetting something, I'll come back and post if I think of it.
Good luck. This isn't easy.
