If you go to a therapist they shouldn't even be telling you to take pills. If pills are being prescribed on the first visit (when no one has been hurt and you clearly aren't at risk of going to jail) then you have a shit therapist who is just trying to farm people for money.

As for actual anger management, you should always work on different ways of interpreting things so that they don't become offensive to you. Lengthening the fuse won't really be helpful if too many things set off the fuse. When it comes to misplays costing you the game, it always helps to see it as a learning experience (or potentially as a game you'd have lost anyway since there was no telling how your opponent might have reacted had you even done your "correct" action) instead of as a one-time missed chance that you personally ruined. How you frame things deeply affects how you interpret them.