Partgypsy,
I'm the victim of adultery from my ex-wife after 24 years of marriage, and as you will see, and I hope never forget reading the stories on Chumplady:
And (he) often feels like he made the shittiest, most selfish biggest mistake CHOICE of his life.
He CHOSE and planned this; lies, deception, risking your health, selfishness above honor, truth and love... Never forget this.
In no way am I criticizing what you wrote, only that I'm sure you know what I mean by my additions. I want to give you hope, with what may well be the most challenging experience of your life... You don't get over this; you go/get through it. No matter how dark it may get, no matter as in my case children being weaponized against you, thrown out of your home by lies, witnessing a near violent confrontation at my home from the other betrayed spouse, gaslighting and outright and complete lies are told to your children, family, even the courts, you will emerge wiser, and stronger concerning many things. You too will learn that you do not have to forgive anyone, especially, gulp, a 'person' who could commit perhaps the most painful act of premeditated emotional rape, that can be imagined.
Please never waiver, ever think the devil you know is better than..., or as mentioned ever consider being plan-B, or accept one atoms worth of blame. 100% no-contact will be your savior, where you will find strength, true clarity, and shelter from the storm. Also, please know that even when you go from sobbing a bottomless well of tears, then 20 seconds later experience a white-hot homicidal rage it's normal, and OK. Please make sure to eat as well as you can, drink plenty of water, and try to stay away from booze/drugs. I lost 50 lbs, and literally thought my heart would stop many times. believe-it-or-not, one day this person will be just a name, just a person you knew, and it will happen on a Tuesday (the last bit you will gleam from CL). You are not alone, and please if you feel the need to talk/vent to a non-judgmental stranger, who absolutely gets what you are going through and cares, please PM me, or even call if you need it. I wish you peace.