Before you go to bed tonight, take the time to sit down with a pen and paper. <– Seriously, nix typing this on the computer, and ditch the tablet and smartphone. There’s something insanely cathartic about doing this completely by hand.
Make a list of no less than five things that were happy, positive, or just otherwise didn’t fucking suck (a positive outlook has to begin somewhere, right?) that happened today. Bonus points if you can come up with a list of non-shitty things the object of your anger did.
Do this every night, or at least a few times a week.
Feel the anger dissipate. You don’t have to forgive to understand, and understanding will help you to move on and make the best decisions for you.