Mamakal first you just need look you life other way and it won't fail, if you don't let it fall.
Second you will get better grades, if you read, but that don't mean you have to totally quit everything else. Just make time to yourself and do things what you want and then when you had time yourself and done all school stuff, come on computer.
Last one addiction is bad thing, but you can't quit, because then you will live in one kind of jail. You must be less on computer, but not quit and if you don't think you can handle it that wait. Just be away from computer like a week and then come back and do this kind of things as breaks or get professional help.
And about report card. There ain't any reason to get that, because life is for life. You choose yourself what you will do and when, but there maybe is some borders, but they are far beyond of you. Now get up and did thing like that.