Practice mindfulness to learn to prevent unwanted thoughts from distracting you, and learn to confront and accept memories that are emotionally distressing (therapy can help with this).
I like the first option. What I do is don't worry about forgetting. I let myself be as angry, frustrated, sad, whatevs. The biggest help is decoupling feeling from action. Just because I am angry, that doesn't mean it'd be a good idea to aim my anger at someone else. Then I just move on. Getting the emotional stuff out of the early frees me up to remember something without getting all emotional about it. Eventually I just have too many other experiences to process before I get to the thing I'd prefer to forget.
