I think trying to lame blame at who's at fault for the D to your kids are a bad idea. I don't think they will have as much of a reaction as you think they will, it seems like in most cases they just listen to what is said and then move on... But I wouldn't try and add more for them to think about than necessary, the M is between you and W, not the kids.
However, if she decides to try and throw you under the bus, then I think it would be prudent to clarify any errors she may lay out to them. but it doesn't seem like WW try and hurt the R between the Father and child.
M - 9 1/2 years 5/5/16 - Bomb drop - 3 week EA 10/31/16 - We sold house 01/10/18 - D Finalized