40 something y.o. and he has dinner with Mom most nights? This guy really isn't available for a romantic relationship with any woman. He's "already taken."

IMHO the nature of your relationship with him needs to keep evolving. Maintaining a "close friendship" with a former dating partner is not a great idea. Lots of posters in these forums will say, "Why not?" It comes up a lot in threads. It just never seems to be a good thing.

Here is another thing I would recommend: Adjust your FaceBook access, so that what you post no longer shows up in this guy's mother's feed. He's in a weird relationship with his mom. There's no need for you to be. Disengage with her, gently, politely and firmly. I'm not saying "Unfriend" her. Just quietly close the door between her space and yours.