The fact that she puts on the happy face at your house to me is almost to be expected. My XH told me it was extremely hard for him to be at "our" house (mine now, he hasn't been there since I bought him out on the mortgage)because all around him was evidence of what he gave up and what he was risking for the OW/other life. There was something he said every time he saw me at the house during the divorce proceedings: "I can't live in two worlds." One time he actually said to me "I had no idea you would change so much in such a short time. But I can't live in two worlds." I'm not trying to mind-read but he said that after learning that I had done a bunch of 180s on the very things he complained that I'd never change--but I did.
I think in my house, he felt regret that he pushed away successfully elsewhere. So generally, I'd see the fakest display of happiness ever when he was there, which to me makes sense, because it's the place where all around is evidence of the comfort and the good things, the home, and family, that he left. To keep from falling apart, he would put on a big act.
I bet your wife may be doing the same thing. It's part of the whole "I'm right and I know it" mentality.
M45 Bomb 6/09; EA 6/10; Divorced 1/11 Proud single mom of 7 little feline girls and one little feline boy "Fall down 53 times. Get up 54." -- Zen saying