Hi Erin, I had to respond to your post as it really hit home for me. My H does the same exact things, and I really felt bad when you mentioned your H talking to OW while watching the baby. That kinda thing kills me with my H too. And I also understand when you say:
"he is talking an e-mailing with her compulsively and daily. I mean, is there a better way to fall out of love with someone than cutting them out of your day to day life?" - but I do tend to believe (maybe too optimistic) that while the WASs may TRY to block us out and forget everything by being so wrapped up in OW - that it will likely prove futile for them. These crazy, obsessive Rs with the OW are not based on any solid ground, and infact are rooted in all of the confusion of the WAH's totally unresolved feelings about US. Somehow, some day, they are bound to fall apart. I like to imagine that my H will eventually (if I can manage to go dark as planned!!) start thinking about me when he is with OW more and more, if he doesn't already. Your H seems as confused as mine, so I think that may be the case for you too! If the OWs are bandaids, well, bandaids don't heal, they just cover up. And they certainly don't last...
Stay strong, and good luck!