It would seem like she is a smart woman, & being so, she's been able to piece it all together. I think the worm really turned for her when he gave her the "I'm the one who knocks" speech
That speech was almost entirely for her character's benefit, because it was, at that time, still somewhat bullshit that Walt was spouting out of his ass for dramatic effect
It worked, & then coming out on top of the chicken man in bloody brutal fashion was the kicker. His whole attitude has changed, & everyone has noticed it
Even Jesse looked concerned at the end of last week's talk about Victor. Certainly the wife would pick up the clues much sooner & in her case be much more worried about it
Yeah, when he says "I won" in that cocky, arrogant way he did, it was probably the first time she realized that "Oh shit, this isn't just him putting on an act anymore. He really HAS become a different and more dangerous guy now."
And again, exploding a bomb in a building
usually does make people question your sanity and judgement, I find. Regardless of the threat Gus posed, that was still an extremely reckless thing to do.