How do you let go of those feelings of resentment and hatred towards someone and keep up NC when you get so worked up??
Sheer willpower at first - you fake it till you make it and one day you realise you're not faking it.
The root of most anger is a deep hurt. Realising that helped me see that in unleashing hell on him I was showing him my underbelly. That fucker won't be seeing my underbelly every again in my life.
You also need to make sure to stop people when they give you ANY info about him. Curiosity killed the cat, as they say.
It is not easy but NC = No New Hurts. Remind yourself of this when you are worked up.