Excuse my french here but I have a tendency to hold onto things for far too long. Are you like this too?
Don’t let the actions of others from years ago affect your present day. They have probably long since forgotten what they did to you to make you angry.
Anger is like holding a lump of hot coal hoping that it will harm the other person.
If the situation is something that you can do something about then it makes no sense to worry about it. If the situation is something that you cannot do anything about then worrying makes no sense as well. So what does that leave out? Nothing! So chuck it in the fuck it bucket and move on!