America is place where you will succeed if you keep on trying. don't loose hope. don't think negative. keep on doing what you are supposed to do and one day you will achieve something. If you loose hope, go back , start using drugs/drinks then i can't guarantee you but if you keep on your right way you will get it.
and trust me brother you are not only one on that situation ! there are so many of us been there are some are still there , but as you said there is light at end of tunnel; this (US) is path where you will get your all payback at some point. Dhilla chado ko kura maatra ho .