Hi, winniemac. Sorry you found yourself here with the rest of us, but I hope you receive the support you need.
I know about the ambivalence. Like you and your husband, we were high school sweethearts. She's the only woman I've ever loved - there isn't even a close second. But, like you, I find myself having to deal with a situation that is almost unspeakable. And the thing I regret most about it all is that my feelings for my wife have changed.
Before her affair, I absolutely adored her. Everything I did was for her and the kids. I treated her like a queen (her words) because I loved her with all my heart. Literally. Now I have days when I feel nothing - like I'm emotionally comatose. I know I still love her, am still in love with her, but it's different and I don't like it. I suppose it's because I always thought our feelings for each other were on the same level, but I was obviously and painfully mistaken.
My wife and I are doing well in recovery, she tells me she loves me and knows how poor her choices were, but I don't know that we'll ever again feel the same spark we used to for so many years. Things are different now, and they always will be. So tragic.
But that doesn't mean I'm going to stop trying. I still believe God joined us together for a reason, and I'm going to trust that restoration of our marriage will happen in due time, and, with that, perhaps a re-discovery of that spark. I really miss it.
Your husband is trying, probably more than my wife is. That's a good thing and allows for you to have hope in the rebuilding process. So, I guess if I can offer any advice, it would be to keep faking the feelings until they come back in earnest. That's what I'm trying to do.
Hope your OK days start to occur way more often than your sad ones. Take care.