Is it in your power to make things stop? I´m not saying "don´t stand up for something when you can´t make a change", I´d say "stand up for something because you feel that it is right" because you know that your believes are in the right place or because you want to support someone. this is a typical thing that happens in a crowd, we are all sheep and we all act like it. there are very few individuals who are really brave enough to BE THEMSELVES and always act true to themselves, it takes courage, let´s admit that but it is not always wise. why? because you have to survive. sometimes we feel ashamed for acting like that, following the crowd, not wanting to stand up, we fear that we will be ostracized and it is understandable. however, don´t mind my pseudointellectual words.
this is high school, wild, dangerous place. just because the jerks are jerks this year doesn´t mean they will be like that next year. people get educated, they get better, they change.
you need to sort your thoughts out and set your priorities. keep an eye on the person and maybe let them know you are here to support them and say that you are sorry for not being too loud about it, but that you don´t feel competitive enough to do so, but if they need someone to lean on, you are here and you want to be here. let them show you what they need and be careful that the comments don´t turn into bullying.