there is a hole in my heart, in my family, and in my life that my husband used to fill. It doesn't go away
I agree the betrayal and subsequent overwhelming grief are in no way 'easy'. But that doesnt have to be your life. Even holes in the heart - while they dont magically 'go away' - can be mended. I have found some world class surgeons here at MB who have talked me through the process.
It gets worse every day, not better, Moving on doesn't just seem hard to me, it seems impossible.
The rollercoaster dips very low at the start before it goes up again in Plan B, (I thought I might have a nervous breakdown) you have to break yourself down, cut out the poison - cutting deep with no anaesthetic - in order to heal.
I cant advise you on the kids thing with Plan B, having no children myself. Obviously the things they say will trigger you and triggers are what you are trying to avoid.
There are lots of people here though who have got their hearts back even with kids in Plan B, so I will let them lead you on advice.
Does your WS have a nickname? It helps actually. Mines is Softlad, Scotty's is Bampot.
So you could for example call yours 'wayward alien' and not let yourself say his name. Then perhaps if when your kids say to you 'dad did x today and then said y' Mentally repeat it as 'Wayward alien said x today and then did y' Then add to yourself 'Waywards! That fog is good stuff' Dont let your thoughts follow any trian where you give him his old name - not until he reclaims his old character. This might help you to detach more.
However I think you have to do some grieving before detaching.