Yeah, I don't see this ever playing out even if awkward MC spills out everything and tries to make this right. All the toxic wife wants is to stay on the moral high ground, to always be in the right, and use her husband's mistake to drain everything she could get from him, money, resources, and otherwise. Hell, she's using their own daughter as leverage to give her 'needs' more weight, not even considering what's best for her, just as the teacher pointed out.
I actually know someone like this, let's call them A, and I try to avoid contact with them, even though it's been long after the person that wronged them (the awkward MC in this scenario), B, has left this world (not by suicide, but they pretty much destroyed themselves to get to that point), especially after learning the stunts A themselves have pulled long before that.
The wife here may seem lonely now like she was at the art gallery at an earlier chapter, but just wait a couple years once the husband and their daughter leave the home, not wanting to put up with her bullshit anymore.