I completely understand your struggle and I am certainly no expert on controlling myself especially when it involves chocolate. I am guilty of constantly giving into temptation and have lost and gained the same 50 lbs. over the past years.
The only thing I can suggest is:
1. Forget about Starbucks. What is done is done. Just move forward and try to plan ahead to avoid being tempted in the future.
2. If you can bring yourself to do it, take the chocolate and throw it into the garbage can or give it to someone else who is not in the house. Then you won't have to think about it any more.
I have spent a lifetime being overweight and regretting giving into goodies.
I am starting over again and I am trying my best to remember that losing weight feels better and is better for me than enjoying chocolate for a few moments.
I am thinking of you and supporting you.