Thank you Steve and ovrrnbw. I appreciate your input and advice. I have only contacted him three times since he left and all were necessary communications about the kids and the house. Other than that, no good mornings or good nights or I love you's which has always been our thing. I will continue to keep my communications to a bare minimum and business-focused.
I have been thinking about the OW thing too. So far, no one has caught him with anyone. My sister and her H tracked him for two weeks straight and my friend, who lives just around the corner from where he is, regularly drives by and walks her dog past his place and has never seen anyone there but him. However, it is completely possible that he could be having an online EA if not one in person. I have also been watching our accounts and VISA like a hawk (I've always done that so I know his spending habits well). He has only had access to his own money since the middle of May but prior to that, he had no access to anything that I don't have access to. All of his pay cheques go directly into our account and I know where all the money goes. There have been no big withdrawals ($20 here and there) and no strange charges to our Visa bill. This was the same when we were in our former home in a different city. So if he is seeing someone, she is paying for everything. And...he has always looked ill and depressed to me save for the eight months he was home prior to this spring and I would think that if he was in a "new love", he would have lost weight (he has gained) and looked a bit happier? I asked his mom about the alone time issue and she said that even as a child, he has always liked to spend hours by himself. He has a ton of hobbies and interests that he gets absorbed in so I can see him losing himself a little bit in that. I also think, knowing my H like I do, that if there were someone else, he would be a bit less conflicted about leaving and he would not have texted me last week about being ashamed and sorry and wanting to come home even though that only lasted a couple of days.
But, you are right, it is still a very real possibility. I think, though, for my sake, I am not going to dwell on it or torture myself with the possibility of it. In my mind, it doesn't really matter as it doesn't change the fact that he is gone and that I need to start focusing on myself and the things that I need to do in case he never comes back.
The good news about my H is that he is continuing to go to counselling so he is still recognizing that he has some work to do. I go past the clinic on my drive home and his car was there on Monday. He has also talked to me about some of the things they are teaching him in his group (his 3rd session is tonight) so I know he is still going to that as well. He is supposed to go there tonight and I will see a parking charge on our Visa if he goes like I did last week.
Anyway... again... thank you so so much for your replies. It really helps to know that there are other people out there going through similar circumstances and surviving... even thriving. I am very grateful.