Val pre-breakdown: she seems like a nice girl who's completely out of her depths. I'll help her.

Val post-breakdown: Oh. She's. Hm. She's going to become a prinny when she dies.

In all honestly, he didn't particularly mind her throwing a huge fit when she was found out. He works with murderers and worse for his job so it wasn't emotionally damaging to him. He just kind of went "Ah. So that's how it is."