Welcome to Healing Well silver lining, we are happy to have you join us here. I too grew up in an upper middle class neighborhood and was a cheerleader in high school for the first 3 yrs. I dropped out of the team in my senior yr as I had so many pressures and things going on at the time. When I was in HS there was a lot of pressure to be thin and my self destructive behavior was an eating disorder that one of the girls on the squad showed me how to do freshman yr. Self mutilation wasnt as noticable back then as it is now but I am sure there were kids who did this.
If you know that your depressed you need to speak to your parents or school counselor and try to get some help for this. There is no masking depression...you can put on a pretty, happy face and smile for everyone when required to but if those nasty feelings are still there then you really need some help. I dont know what escapes you mean in your post for the depression but any kind of self destructive behavior will only make depression worse and once you start self harming it is so hard to stop. So I really hope that you havent done any kind of this. Please do speak to your parents and let them know what is going on...I am sure they would want to get you some help if you spoke to them regarding your feelings.
As for your friends who are hurting themselves...I will leave you a link at the bottom of this post so you may forward it on to them and hopefully encourge them to call. It is a great site for those who need help in this area. I know it is hard when you have "clicks" that you run in to be yourself as you want to fit in with everyone else. Being happy, perky and hyper all the time is okay if that is the real you. Do you have a friend or two that you can sit down with and just be yourself, talk to honestly? Not feel that you have to perform or always be in a good mood? If you do, then you may want to try talking to them also...those are the friends that would most likely keep for life.
Please do post again and let us know how you are doing. And I am sure that other members will post some suggestions to you also. Take care
http://www.selfinjury.com/index.html
http://www.teendepression.org/