For what its worth:
"Lingering resentments are like acid eating away at us."--How Al-Anon Works
You may have held your anger toward your XABF for days or months, maybe years. I held resentments toward my abusive parents for decades. I'm grateful that I eventually "got it." My resentments, that I'd spent so much energy pushing down, holding onto, & avoiding, were only hurting me. I made a decision to forgive my dad after 30 years and it was like a weight being lifted off my shoulders. The other quote I like:
"Forgiveness is a gift we give ourselves."
Forgiveness doesn't benefit anyone other than me, and the person we're forgiving doesn't get anything out of it (they often don't even realize that I'm holding a grudge).
How did I get that realization? It's not simple, there's lots to learn, it takes time, patience, and you have to learn to love yourself. I "got it," eventually, because I have a program.