A little wobbliness from the weekend, indulge me one question

I faced several triggers this weekend centered around football/tailgating weekend in my town and things I used to do with the XNBF as a couple. This was undoubtedly a big party weekend for him, and unfortunately, I know he was out and about most of the time due to the fact that he's my neighbor and I have to see his house every time I go somewhere. I held strong, NC, though, and I'm proud of that. And I'm focusing on myself and the breakthroughs I've been experiencing since going NC for real this time.

HOWEVER, one of the things that was helping me in coping with thoughts of him reconciling with his W was all the overwhelming evidence that he is just chomping at the bit to cheat on her again. I do NOT wish her pain in any form, I truly wish she will see the light with him and start on her own journey to healing. But, now that I'm no longer contacting him, I'm losing that reinforcement of what a jerk he is -- oddly, for me, the last 2-3 weeks of intermittment contact had been more about building my case against him, that he is truly a narc, and not in any way trying to get back with him. (Moreso get back AT him, but I am over that.)

Anyway, now I'm starting to have these intrusive thoughts pop up again that maybe he *is* trying to be a decent family man but just gets tempted. Maybe he really is establishing a good connection again with her. Maybe he is fully satisfied with his life right now. I know that 1) I shouldn't care a rat's ass what is going on his marriage and 2) I need to focus on me. I am definitely taking care of #2 (okay, that sounded weird, lol) but I have to admit -- there is a part of me that feels all this is easier to walk away from knowing that his mask will slip again with her, that he's no prize, and that he is likely pretty unhappy with his life.

For those of you Ws or XWs of narcs, what was it like after he reconciled with you following an affair? I assume the mask slipped/dropped again at some point, otherwise you wouldn't be here, right? They do NOT change, right?

Thanks for indulging this rather wobbly question. I am trying to stay strong and keep my head in the right place and the eyes on the prize (ME). Just need some reinforcement today.