My mentor told me to do the following whenever I felt angry and needed to get rid of it.
Anyone who does this may never ever need a shrink.
1. Sit down in an area where you will not be interrupted for at least/up to 3 hours. Phone off, TV off, no kids/wife. You are going to write letters to anyone that comes to mind about anything. But you do not mail them. Sit down with a blank notepad and just write down anything that comes to mind. You will be shocked and even swear words should come out. It could be anyone who is no longer around too, even dead people who have wronged you. Don't interrupt yourself, or care what is being written. Keep the notes for actioning later on.
2. The next day, sit down in a quiet area again as per point 1 (or whenever you can next do it) and rearrange whatever you have written and group them so they are all relevant to the person you dislike. Rewrite it so it makes sense to you, but do not send anything, just write a letter to them so they will understand what they have done is not good and anything that had come out in session 1. Keep the notes for actioning in the next step.
3. Rewrite the letters the next day (or whenever you can next do it) but this time you add in that you know why they did what they did, and that you forgive them. Once again you are not to send the letters. Keep this private from everyone including your wife. Some could be things about your wife. And when finished destroy the letters by burning them safely. You don't send them. Burning them releases the anger.
The result? You will feel better.