Here's my only concern for you preggo. He's showing so many positive indicators and still shows concern for you... But if you are upset when he's home and he knows its his fault he's going to feel guilty and start avoiding being home to avoid feeling that guilt.
Acting upbeat and not showing your pain right now may be the hardest thing you ever have to do but you can do it.
I never bring up OW because it will not bring us closer and she's irrelevant. Part of the allure of the OW is how it makes our men feel about themselves. They don't nag, or cry or make them feel guilty. They fluff their ego's, make them feel manly etc. Its our job to find ways to make our H's feel good about themselves even when it feels counterintuitive.
When you catch yourself thinking about OW try visualizing a stop sign and force your mind to think about something else. Also look for other things to occupy your mind right now. For me that meant reading books (fiction, not relationship books ) and I started acting like a tourist in my own town going on tours, trolley rides, etc. These things gave my mind a break from thinking about my sitch and gave me some non relationship things to talk about when I did talk to my H.
BD: Aug 2012 Separated since May 2013 S born Aug 2013 Aug 2013 H agrees to consider 'baby steps toward working things out' H is/was actively seeing someone?