I'm glad your daughter had fun camping. I am sorry you didn't get to go with her.
In my opinion, some of the things you described your mother doing to you and your brothers as children do sound abusive to me. Definitely inappropriate.
You absolutely do need to set boundaries with her. Even if there has not been anything inappropriate, you still have the right to decide how best to parent your daughter. Your mother to respect your wishes regarding language and behavior around your child. You have the right to demand that.
I find it very strange that your therapist would say things about other patients to you. They might say, "some people with DID ________," but to say "patient x did this," seems odd to me. Have you ever confronted him about these sorts of statements? It is his responsibility as much as yours to work to build a trusting relationship. If you could be mistaken in some way, or he has legitimate reasons for statements he's made, he should be willing to clear this up. If not, then I wouldn't find him very trustworthy either.