I'd probably begin considering him like a guy I don't know too well, but am sort of interested in, and ask him out on a date. Make it just dinner or ??? And then start slow like friends. I wouldn't pursue (just like you wouldn't pursue someone you don't know too well). I'd ask him and if he couldn't make it I wouldn't be upset, just say, "Well, maybe some other time..." And then let it go. Maybe not ask again for awhile. Or ask in a way that's very open and easy. "Hey, I just happened to be free on ..... if you're free and maybe a little bored how about we go....."
And then NO relationship talk, listen listen listen... and be a friend!
From what you're describing, it almost sounds like depression or some hormonal imbalance. Is something worrying your husband? Health issues, other family members with health issues. From the limited information I've gathered about your sitch, he doesn't sound like someone in an affair. There's usually more anger....
I have to look more closely on what you've written on the MLC board when I have some extra time.... Making pumpkin bread right now!
There is no arriving, ever. It is all a continual becoming.