ok so I’m pretty sure the dad knows it’s his ex wife thos this probably won’t be revealed for a bit. Here’s why I think he knows.
1. The maiden name on their marriage certificate is the same as her new identity.
2. She’s a nurse, something that the mom has verbally expressed is something she wanted to do before she had a kid. While we only saw the mom tell her kid it’s very likely that he knew this as well.
3. This might be a stretch but I’m pretty her nurse office desk setup is the same set up her son had in his room (it’s even the same desk model with a similar window placement). So he looked at the nurse room and instantly figured it out. That’s why his face is so sad
Or it just reminded him of his sons room and that’s what made him sad.
Her new appearance will probably throw him through a loop and give him doubts but will inevitably reach the same conclusion