Ineed this is i dont know what to do with myself anymore im in a rehab right now and i used to use uncontrollably i just dont think i should be here anymore

Do not give up on Rehab, remember these people know what you are going through because many of them have gone through the same things. having support while your in Rehab is the best thing for you. You helping new people in Rehab is what will help you as well.

If you used to use uncontrollably, that's great! Even the littlest progress is progress. Battling with not only the physical effects but the emotional effects as well is definitely very hard. Just know that you are worth it and that you can do this! You deserve to be here. <3

Other than that, I do recommend that if not already, that you see a professional in terms of therapy if rehab doesn't cover that aspect. (As much as I love to help, I'm not a professional in this field so I can't help very much, unfortunately.) Along with that, surround yourself with people that'll love and support you throughout everything. It's not weak or 'pathetic' to ask for help, remember that. I myself am wanting to go see to deal with anxiety. Hopefully, you'll be able to discover new ways to help and cope with your feelings and not try to shut them out or bottle them in. Additionally, you could possibly get a new insight or two from said professional or learn something new. 

You can do this. A random person from the internet believes in you. :)

Paranoid schizophrenia i believe