I missed the episode when they showed Constance's husband Hugo. It appears Constance shot and killed Hugo and Moira, both of whom she suspected were having an affair with each other..
It was more than a suspicion. She walked in on Hugo trying to rape Moira. He was on top of her, with his pants down, etc.
It was revealed that Hugo and Moira had previously slept together on a more consensual basis, but now Moira was trying to call off the affair. Unfortunately, Hugo wasn't taking no for an answer . . . until Constance walked in and shot them both.