Hi BBJ. I've dropped in on your sitch a couple of times these last few months and would like to waterboard your Dan a little bit.
W and I are in the process of D and we had some people recommend tell the kids now and have a happy holiday season anyway and they will see things are going to be OK. Then our MC said maybe we should wait so as to not link the holidays with the D in the little one's psyche. We chose to wait.
It's a little easier for us, Mom has been out of the house on "sabbatical" since mid April. It started as a break from being a SAHM and turned into her not wanting to be married to me anymore and 2 OM.
I can empathize completely with your desire to not be the homewrecker, but, if you can give it another couple of months, it might pay dividends for the kids down the road.