I have to laugh at how true this is. About 30 years ago, Buddhist me and my peaceful yogi friend were both going through major breakups, with our respective partners leaving long relationships for younger women. I can't tell you how many revenge fantasies we entertained, like would it be better to kill him outright, or kill the new GF to cause him more suffering. Of course it never went beyond the fantasy stage and we both eventually healed over time and remarried, but when you're in the throes of profound loss and betrayal, the mind does crazy things.
For those who might be in a similar situation, I came across this book twenty years later, with insights on that time of great trauma: Runaway Husbands: The Abandoned Wife's Guide to Recovery and Renewal by Vikki Stark