That she cancelled retroville isn't really a bad thing. To go when she has no intention of really particicpating is a waste of time, money and a lie. A 2 day marriage encounter wouldn't "fix' anything. IMO you are looking to see if it's important enough for her to try. Right now, no.
You sound like you're done and want this to be over with. I've got some news, even if you D. It ain't over till the fat lady sings (and I am not even close to being warmed up here ), which in you case is another 11 years (minimally) of enteracting with her. Then beyond that, weddings, births, special occasions... you get my drift here?
I get the anger, she's having a good time and you're dealing with the boys and having to take care of everything on top of all the emotions. I so get that.
Do something to work off that anger. Lift weights (teach your boys), play a sport, whatever it takes to clear your head.
I got the original bomb right after the holidays. H waited until agter the next years holidays to move out. I don't think it matters why she wants to wait. It gives you an opportunity (I know you want to smack me here) to be more compassionate that she is in crisis and be less reactive to anything provocative she might say or do.