"I agree that I shouldn't put them in between us, and I don't believe I am."
You don't think you're putting them between you two, but you are. Your resentment (which is understandable) is building in you and creating a wedge.
"She is using them - she has gone so dark that she doesn't communicate about school activities."
How is this using them? Just because she's asking you for money for support isn't using them.
"When something happens regarding school activities that requires my assistance, I ask why am I being asked to participate in this at the last minute only to provide relief or support that nobody else can? She just gets frustrated and says "well you should have asked me about this." That's right, ask about something I didn't know was occurring in the first place. Makes sense."
If you are doing something for the kids, then do it for the kids because you want to. Not as a way to keep score or to nitpick what she does or say.
"My derogatory comment about her is a reflection of her as a W, not a mother."
If you keep seeing that as how she is, then it will affect your view of her as a mother. You already are by your "she's using them (the kids)" statement.
"I think my W is a slut."
Again, I get the anger. So why don't you just end it? If you don't figure a way to get rid of the anger and resentment, the pressure builds. That's why you haven't made any positive steps with your W's interactions.
"She wakes up one day and decides it would be more fulfilling to be a slut than be my wife. I'm not at the 'shrugging my shoulders' point of it yet."
If you really believe that it happened "all of the sudden", then you haven't learned anything.
M-43 W-40 2D - 9 and 5
Emotion, yet peace. Ignorance, yet knowledge. Passion, yet serenity. Chaos, yet harmony. Death, yet a new life.