slow down, take a deep breath. when those loser feelings come up, see what they are for what they are. spinning out feeling like a loser is not going to help you. mistakes are for learning from, not for beating yourself up.
i stand by my suggestion to get additional, NON-JUDGEMENTAL, help from a professional. you will not regret it. you can also fast in there on days you are feeling strong. don't let the days when you don't feel strong negate the days when you are successful.
the more you concentrate on the strong days, the more strong days you will have. god that sounds trite, but it is true none the less.
you can get yourself out of this. you are stronger than you yet know.