Samuel is right- high school will be over in a couple of years (although I know it seems like a lifetime, right now!) Focus on preparing for your future. As for your friends, you cannot control what they do. Ultimately, you must make your own choices and accept that others do the same, sometimes with unfortunate and truly sad results. But, as I recently told a young woman who'd left a gang and was worried about her friends- she had to look out for herself. You must do the same.
Personally, I have found great comfort and guidance in my spiritual beliefs. Your 'inner voice', if nothing else, can help when you are confused and worried.