Help about high school

I am in a bad situation right now. Last year in middle school, 8th grade, I really came out of my shell and got more outgoing, and I even got a girlfriend. Now, that relationship ended and I’m going into band camp and high school. For one, I’m terrified because it’s 10 hours a day every day and I pretty much spent summer alone on my room most days, so I don’t have many social skills. And also I’m worried it’s going to be super awkward with my ex because we’re the same instrument and we have to do everything together. I just really need some support right now because I’m freaking out and I’m scared.