What is wrong with me & how do i get better, please im desperate.?

Sound like you have a lot of issues controlling you right now. Too mainly honestly I think that you can address on your own. I really think you could benefit greatly by checking yourself into a mental health facility for say maybe a week. That way you can get therapy 24/7 and there wil be people there who can observe your behavior and get you on some corrective meds. The overdosing part and self harm really worries me. You can get help.Try going to Your local ER and telling them what's going on. They can be sure you get to the kind of facility you need to be in. Good Luck!