I don't know if this applies in your case, but some times dysfunctional families have gotten comfortable in their dysfunctional way of life and when one member changes for the better the rest of the family gets scared. So they will do what ever it takes to keep that one member in their appointed role in the family. This is not usually a conscious process on anybody's part, it's just their way of trying to keep status quo. They are invested in keeping things the way they are and like My kids are cool said it gets worse for a bit, but usually things move forward after a while. I was the one who broke the rule of silence in my family and it did get rocky, ( my grandparents moved here from Germany and the rule was; at all cost you don't let outsiders know what goes on inside the family, you don't show pain to outsiders) our relationship has never been better, it's far from perfect, but everyone except one sister has grown much more accepting of life.

It's hard, but it's sounds like you have a wonderful T and support system in place. As scary as it is it sounds like a good time to try to try something different than what was tried in the past.