I've been having homicidal thoughts
What's going on in your mind?
I'm a crazy man. I want to know why others have better lives than me...
You shouldn't compare your life to others, especially to their social media.  But if you are having unusual thoughts, I think we should find you some professional help.
Actually I'm doing well in school and have a great friend circle.
Well, that's very reassuring.  Remember that others only show you the highlights of their lives, and that you are similarly lucky in your own way.  If you actually think about harming others, though, you should definitely talk to someone.