He WON'T feel the love, so long as he is in contact with your sister. That's a physiological FACT. Right now, his brain is all awash in PEAs (looove chemicals), and it's masking his feelings for you, and he's RE-WRITING YOUR MARITAL HISTORY.
It's all SCRIPT.
I know, it doesn't make it HURT any less, but please don't take what he says about "never" having feelings for you to heart.
Personally, I'd advise against YOU telling your sister. I think your position with your husband right now needs to be "this is YOUR mess; YOU get to clean it up."
I also still don't know if I believe him when he says the feelings are one-sided.