Prayer is not meant to be used to push the anger down into our body, which is what happens. When you give yourself over to an addiction, you're not there anymore. The addiction deadens all emotions. We are afraid that if we express our anger, we'll hurt somebody or ourselves. After all you are not angry at them but at the behavior - not the person.
Feeling is the key to getting over it.
Use the telephone and call a friend or writing about your anger. The person who hurt you in the far past should be worked out with a Christian counselor and not calling them and yelling at them. Forgiving may take time but it will come.