I can only speak from a mans viewpoint on ME personally. I failed to bust the affair with OW with my husband so I cannot give advice there whatsoever - I failed.
What worked on me was him telling me outright it was over and he never wanted to see or speak to me ever again as long as the affair continued. I got VERY AFRAID - remember we had kids together and he was basically saying, I will not SEE you or SPEAK to you even in relation to the kids - I will go thru someone else to get to you; I wont TOLERATE you.
he literally LAID IT DOWN and frightened the living crap out of me. he said he was DONE and if I didnt give up the OM he was COMPLETELY thru with me and get this: he said: YOU WILL NEVER HEAR FROM ME EVER AGAIN. EVER. he told me he would initiate a "go between" for the kids and I would have NO ACCESS to him, his contact details NOTHING.
He took a very hard line and it shook me up so much I ended the affair IMMEDIATELY. i couldnt imagine not ever seeing or speaking to my husband, ever AGAIN but i saw in his eyes - he meant every single word of it. He stood up to me and toe to toe and to give him this, I KNOW to this day he meant every single word of what he spoke; he wasnt one to say such lightly. SOME women (pls dont bash me im just saying some) NEED direction to snap them out of it and I was just such a lost soul who NEEDED to be given a hard line; it WORKED on me. I would not say it would for everyone; but in my husbands case I knew he would follow thru with this, and this was someone i knew for 20 years. I couldnt imagine for a SECOND not being able to contact him or speak to him AT ALL.
so i ended it. but not without emotional angst of course and a lot of carrying on that I thought he couldnt 'see'. he saw alright. a lot more than I thought. no one ever gets that. I thnk that applies to both women and men.
ITS TRUE in my opinion today that sometimes the utter complete HARD LINE might need to come (not so much for women to men, as men are more likely to call your bluff, but defintely so with men to women.) WOMEN are emotional creatures and also creatures of the PAST. we cant get OVER the whole IDEA of complete "no contact, EVER" thing. believe this. we cannot believe that is even a possibility. whereas a man, a man is more likely to be like "OK THEN" and just walk away. Men in general, are MUCH better at walking away.
I think overall in the sexes this is a huge thing neither sex get about the other: women tend to focus more on the past and not be able to move forward (even when rebelling) but men are more likely to "give it up" and TRULY walk away. Face a woman with that and it IS panic time, I dont care if you are in it or not. thats a big deal.
If the affair was fresh i wouldnt recommend a man ever give such a hard line but if its in from 3 to six months I think yes, if shes still ummming and aaahing about the marriage, then yes, give it, yes why not ultimatum, because BY THEN, if she chooses HIM, then she should live with that. experience that choice. Then id go DARK.
In the cases of WOMEN with hubands I wuoldnt give such rash advice at all (as men walk off pretty easily.) I would say yes fight with the whole DB thing, do the stuff. but I think with a woman... going hard line CAN and DOES work if your committed to following thru. a woman would find it harder to find that decision than a man would (about following thru, even if it didnt work out.)
If i were a man who put forth such an ultimatum tho id be very sure in myself id done all i could (to change bad ways etc) been loving offered solutions etc, but if everything is done, the final ultimatum isnt bad (as long as its from the heart and you mean it; if she doesnt give him up your walking.)
But if you take that route just remember its still hard times, as she will be pining and stuff for the OP. blaming you even. its a TOUGH SITUATION, but ultimately if you dont fight dirty and low, you might LOSE to promises of "I will treat you better". (this is so rarely true)
I know IN MY SITCH if my h hadnt given me the final ultimatum it would have carried on. Im glad he did. Emotionally tho I was unavailable for 2 years after.
you have to ask if your willing to hold out for those two years.
after that tho I can truly say true sorrow and regret sets in (for ME) and I think i am not unusual.
When you're down to nothing, God is up to something.