Shortly after 9pm, I heard my cell ringing... This goes on about every ½ hour until 11pm: cell rings, then house line.

I checked the messages. By the third one, you could hear the attitude in his voice because I wasn't answering either phone. He was at work, and said he didn't know if maybe he needed to come by and let our puppy out. [this is ridiculous; he works about 1 ½ hours from our house

Let's see, 1½ hours from 9PM would make it 10:30, by which time hopefully, puppy would've been walked if he needed it. By 11PM, 1½ hrs. would make it 12:30 by the time H could possibly walk him, making the timeframe from 9 to 12:30 that H is concerned that pup hasn't been walked, so concerned that he calls every half hour.

How come he didn't figure you weren't home at any point because you might be out walking the dog, duh?

Ha, ha. Anyway, don't you just love it when they make up bogus excuses to contact you?

When one partner changes the dynamics, the other partner either fights and struggles to keep what was the status quo, because that's where they were comfortable, or has to eventually resign themselves to accepting the new dynamics, in which case they change accordingly. The other thing that can happen is that the partner making the initial change (you) can get frightened and go back to the status quo. That partner may slip back to past patterns because the other partner (the WAS) shows anger or aggressiveness as a reaction. Let them do so if that's how they react. It's the storm before the calm.

once he figured out that I had been home all along he couldn't get off the phone fast enough. Maybe he was embarrassed, I don't know.

Perhaps. Behind that, he realized that the reason you weren't answering the phone wasn't what his imagination had stirred up. You know how your imagination might've gotten the best of you too, in those times when you wondered what he was doing with the OW, and your imagination paints vivid pictures of the two of them swirling martinis and eating gobs of caviar while basking in a penthouse apartment, laughing and making merry?... well, he's doing the same thing.

To add to Spitty's thought: Imagine if you didn't answer the phone all night long, and then when and if speaking to him the next day, you did NOT tell him that you were home asleep all night, but rather, remained very vague as to details and everytime he asked you'd change the topic. What would happen then? Similar in my sitch, look how my ex may be experiencing the sense of losing me, and it's partly causing her to think back and reflect and miss me and regret that things went wrong, and express affection for me, and causing her to mist up some.

I don't feel encouraged about this; I'm just annoyed. If he doesn't want me anymore, leave me alone so I can emotionally get over this.

True, there's not anything notable to be "encouraged" about, it's not like he's made any significant changes and improvements in working on his issues, he's still the same guy he was last week. Letting it annoy you though is unfortunate. Let it amuse you for a change, perhaps? He wants his comfort zone, his safety net, boo hoo. Like the Spitty said, 'you're in control now'.