What should I do?

My two best friends went skiing together before Christmas. I actually wanted to go too, but it was my dad's birthday and we went away, well, for him. I thought it was a real shame that I couldn't go with them, but I also really enjoyed my weekend because I spent a lot of time with my family. We had to prepare for a chemistry exam that weekend. Since that weekend, they've had their own insider tips and everything. We've spent the weekend sleeping over and we're discussing which film to watch, and I suggest a film that we started together once. We always said we'd finish watching it together, but they watched the film on their ski weekend and didn't tell me anything. At first I was a bit playfully annoyed but I laughed on the side but then a friend said that I wasn't going with them anyway and then I said I had to go with my family and besides I was studying chemistry which is why we couldn't watch it together (but they didn't ask me back then if we wanted to watch it together). Then my other friend said that they had also studied chemistry but still watched the film and she had also described an A which is why she thought it was possible. Both my friends know that I'm not as good at school as they are and that I'm sometimes really sad when they get better grades than me. Anyway, my other friend then said that she had also got a C (I got a C). I then changed the subject but I'm still hurt. What should I do now?