I think the only way to survive is to try not to think about OW and that situation. My counsellor actually taught me a thought stopping technique where you release a kite, and I used it. Now when I think of them, I just say, "kite" and it does help most times.
I think it is human nature to want to ask why, to try and snoop and find out all the nasty details, but it doesn't change anything. It just does your head in. I have learnt this the hard way, and still relapse, as recently as this morning But I really think the only way to survive sanely is to DB and not mention OW at all.

My H is in mlc and it is so hard when you are dealing with this. But you will survive, and you will come out a stronger woman. Hang in there. Just take it day by day and even hour by hour.

Smile, it makes people wonder what you are up to!