FWIW telling a one sided view of the sitution damages the children as much as any affair.
DH ex wife was shagging another bloke for years before he met me, he didn't leave because he was scared (correctly) she would stop him seeing the children.
She spent so much time with the OM, the children used to stop in his house on the way home from school, before anyone suggests he was spinning me a line. She told the children it was OK because she was sleeping on OMs sofa - as told to me by SD.
When DH met me - she went fucking beserk, threatened to torch his bike, cut up his clothes, do anything in her power to stop the children seeing him.
We had literally just met, but he didn't fancy more years of sitting by while she fucked another man so he moved out, after 2 years of her trying to throw him out so she could move OM in.
He got a flat and we embarked on a veyr successful relationship.
What did she tell the children, who were well aware of the OM, he used to cut DHs MIL Lawn.
They were in debt up to their eyeballs, but what little money the did have he gave her, 100% of the equity in their home plus initially 50% of his low pay in maintenance.
What did she go on to tell the children??
That DH had run off with another woman, stolen all their money, that he didn't want to pay for them.
Of course as soon as she was actually single OM dropped her like the sack of shit she was.
The children no longer see their father, after years of the poison being dripped into their ears, and despite hard fought for and very expensive court orders.
The youngest is asking to see her dad (at 18), in secret - because she misses him but she doesn't want her mother to know she sees him
He complies, unwillingly, with the secrecy, because the people who suffer the emotional abuse are the children not him.
So yes we had an affair, but it wasn't our affair that damaged the children was it.