You can't be bitter or even angry and grateful at the same time.
One of the best ways to show your gratitude is by using a "Power Thank You." It has 3 parts:
Part 1: Thank them for something specific that they did for you (it can also be something they refrained from doing that would have hurt you).
Part 2: Acknowledge to them the effort it took for them to do it (by saying something like: "I know you didn't have to do ----" or "I know you went out of your way to do ----").
Part 3: Tell them the difference it personally made to you.
Don't stop there, because gratitude like music has charm to soothe the savage (and hurt) heart. That's because you can't be bitter or even angry and grateful at the same time. When you are angry you feel as if something is acutely missing (as in you have just been dissed, disrespected, cheated, hurt, disappointed; when you feel bitter, that anger has hardened into mindset of feeling done wrong and a victim of the world.
On the other hand when you feel sincere and heartfelt gratitude, not only do you feel as if nothing is missing, you feel complete and that your cup runneth over. True gratitude crosses over seamlessly into generosity and wanting to give back and a "Power Thank You" is one of the best ways to do that.
If you are unable to be grateful your anger has begun to harden into bitterness. If so, you need to do some leg work to get your mind, heart and soul on board. The secret is simple, but not easy. Just forgive everyone (including yourself) that you are now unwilling to forgive.

TAKE THE PEOPLEJAM CHALLENGE:
Do a "Power Thank You" to someone you are grateful to.
Share what you did and how it made them feel and how it made you feel
Make a commitment to "multiply" and tell us how you are going to keep the ball rolling.