You can get through this. You will. You have a mountain of worries and trauma on your shoulders, from what it sounds like. I wish there was a magic solution to your issues, but if there is one, I don't know what it is.
I can't and won't promise that things will get better or worse. I will say that life changes, some for the better, some for worse. In the meantime all you can do is focus your energy on right now. The future is unpredictable. Period. I've found that occasionally we can affect a "self fulfilling prophecy" by thinking something will happen. But it doesn't have to.
Again, focus on now. Focus on today. As much as you can. Grades are just letters. If you don't know what you want to do with your life, that is okay. Maybe you're not even on the right path. Maybe you are.
I find that when I get overwhelmed by those awful 'what-ifs', I focus on what is. What can I do now, today, tomorrow... Start small with a list of what you want to and can do. Maybe it's just one bit of homework. Then mark it off the list. It will feel good to accomplish it, regardless of your grade. Maybe you just want to get out for a walk. That's good. Do it.
The big picture of life is SO much bigger than we realize. My mother used to always tell me the old cliché, "Don't sweat the small stuff." (Which used to make me SO mad. Lol) But then she would say, "Just remember, it's all small stuff." And now that I'm at middle age, after all the trauma, hopeless feelings, failures and happiness, too, I realize she was absolutely right. Life is going to take you in directions you never saw coming, some are going to hurt like. H.E.double-hockey-sticks. Some of those moments will be so wonderful you won't believe you could ever feel so much joy. It is truly tough. No doubt about it. But this too shall pass. It will, and you will learn from it and grow, no matter what happens with your college semester.