I'm mad my friend made plans
How does them wanting to do something make you mad?
I don't like when people make plans.
It is good for friends to share things but it is okay for them to keep things to themselves sometimes. It is not okay to be mad at them for not telling you everything. They will be upset that you are even mad at them.
It's fine I'll try to work on my ego.
I'm proud you want to try to improve yourself! They're your friends, I believe you should always enjoy and be happy with them instead of being angry. I'm sure they would love to see your improvement too.