I'm in the same situation as you except way ahead. Crap marriage, I'm ignored. Stay for the kids.
Imho I do condone cheating. I've done everything possible for him including telling him it's ok to go to a prostitute.
I've given up.
My goal now is moving forward, being independent & leaving this marriage. I've lost myself for over 20 yrs.
I hope you find something. Some help. Maybe a therapist some will say. How much time to do wanto put into this & how badly do u wanto save your marriage? Is your SO also willing to save the marriage too or are they clueless.

If you feel stuck that will lead to resentment.