I completely understand how you feel. I'm constantly wishing I could get revenge on my ex and his new gf for all the pain they caused me and awful things they said to me. The best advice I can give from my experience is keep yourself busy. When I'm busy, I don't think of my ex. When I do things for myself that make me feel good, I start to feel better. Also these thoughts will subside so know it's just temporary. You'll come to accept that it's not worth it to waste your time on someone who wasn't deserving of your love. The best revenge is living your life to the fullest and being successful.