I had bipolar disorder and was a recovering alcoholic before surgery.  I have never felt better.  Your problems were there pre op.  They would have come to light sooner or later anyway.  Losing the weight caused you to lose a big defense mechanism and not eating caused you to lose a big coping mechanism.

Using weed to get yourself off of booze is flat out stupid.  Gastric Bypass did not make you that way.  You need a good rehab, 12 step meetings and a willingness to participate in therapy to deal with your issues.  Gastric bypass is not killing you.  Sadly, you are killing yourself.  You would have gone down this road anyway, surgery or not most likely.  Another life stressor would have triggered it.

Please get help and get to an AA meeting.