I am not sure how to advise about re: your W sleeping with your children. Hmmm. I get your point, but 6 y/o and 3 y/o doesn't seem over-the-top to me. Others may disagree.
As for how to inform your children, I think what you posted is good:
"Since it takes two people to want to make a marriage work, and we don’t have that, we have decided that what we need to do is to get a divorce. We love you so much etc"
Children will think it is somehow their fault. I would also mention that it is not their fault at all.
What do others think?
Hang in there RAI!
Bob
Me:55 yrs/W:51 yrs (has MS) M:14 yrs T:15 yrs No children together--3 each from previous marriages Wife Moved Out: 10/19/14 Wife Filed for Divorce: 10/20/14 Divorce Final: 10/21/15