I am so sorry about this latest punch to the gut...it just totally s*cks to receive this kind of information at all, but especially from a 3rd party, and especially in this way. Who knows...could be he's lying and she's lying and the real truth is something different yet. And it surely seems that CW's H could have found out the info he needed without burdening you with this 'extra juicy nugget'.
However, I don't know that confronting H about it will serve you any purpose other than to engage in another black trip down the destructive R path with him. He's lied and been deceptive to you; you both know this. (And he will likely know you know this latest crap, even without you saying a word to him) and may even be looking for more drama from you on this.
Why open yourself up to more of his self-serving, hurtful justifications for his actions? When and why it began may, at this point, almost be beyond the point, unless you intend to prove something for legal purposes. Maybe the big 180 here would be to hold your head high and walk right past this train wreck, literally and figuratively.
I'm thinking of you...hope you can have a good time with your kids at the shore this weekend...