Hi CF. Your anger in this post is palpable, and it is healthy and it is justified. I don't think there is any reason you should have to forgive your cousin for what he did to you. If you have a T that is putting pressure on you to feel that way I suggest finding another T. Forgiveness may be the right path for some but not for others. It may be possible for some and not for others. That doesn't mean there is anything wrong with you. When it comes to therapy and/or recovery and/or psychology in general, a lot of people seem to have this "cookie cutter" view of it all. As if everyone is the same and should have the same path to reach the same conclusions. It's bullshit and is one of the reasons I've avoided individual or group therapy for so long.
I'm not sure what else to say other than I hope you have some kind of healthy mechanism for coping with the anger you are feeling right now because it sounds like it's eating you alive. Whatever mechanism that may be, focus on that. Anger is a gift. Take care. Peace.