Yikes, I can understand why you were so angry at her. Trauma sharing is really vulnerable, and you need to know you can trust her with that information. Anger protects vulnerability. No wonder you wanted to lash out at her.

Just as an aside... our therapist always brings things back to "anything that happens to one of us actually happens to all of us". Our therapist is quite experienced with dissociative disorders but still doesn't seem to get that the subjective experience is quite unequivocal about this - something that happened to a different alter did NOT subjectively happen to me (and vice versa). I get the theory that there really is only one body/one person, but... yeah. Not.
I totally understand your sense of invalidation about the therapist getting another's experiences mixed up with yours. It matters. I am glad you were able to somewhat repair the disconnect with her though.