We learned this week that Tate is Rubber Man, and also that he's working with Nora to get her a baby or two. Hence, why he killed the couple couple: they had chosen not to adopt.
He then set out to make Vivien crazy so she could be institutionalized the the children raised in the haunted house with her. The plan worked. Through Hayden screaming and Tate, as Rubber Man, almost raping her, Vivien lost it.
And Violet didn't back her up because she loves Tate and wants him around. The end result? Cops came and took Vivien away.