Another thing that could be happening too Alisha is that your sister has finally found a person who is really "listening" to her. While you may do that yourself to a degree, you are still a member of the family "dysfunction" and you will see things from your own perspective. So while you care, what your sister needs even more is someone who is exclusively listening to her talk about her entire family, including you and what it means to "her" alone.

If a therapist is really good, not only do they listen but they are also outside the picture looking in and focusing on the patient's needs in their dysfunctional or challenging scenario. A family member can't really do that because they are too "in the picture" and as I mentioned, may tend to emphasis what they see from their standpoint and position in the family. I have this challenge with my older sister and believe me, she doesn't really see "me" at all, but she demands she does and can be extremely condescending about it (that is just me, not implying you are like her in any way).

If a therapist is good, they help a patient be able to step back from the picture and see what it all means to "them" in a more "empowering way", and that happens because someone is exclusively listening to them and validating them the way "they" need it. It is often "for the first time" helping that patient to be free of the bonds that often keep them captive in a family dysfunction.

So, part of what you are seeing IMO could be your sister feeling in more control and having permission to handle her family in her "own way". I understand you find it upsetting and worrisome, however, try to be patient and not expect your sister to go back to whatever role she did play in the dysfunction. It isn't about "your needs" right now, it is about "her" needs and quite honestly, that is how we learn how to heal and grow because we need to learn "how" to give ourselves permission to take care of our own needs because in a dysfunctional family where the parents are not nurturing that is not allowing that to happen, but instead insists on sending out messages that represent to their child that they can't have their needs met and they begin to slowly believe it until they struggle psychologically with their sense of self worth and ability to be their own person.

The problem with dysfunctional families is that what begins to happen is the family members learn to push the right buttons to keep the dysfunction going, and if you can find those buttons and resist, it is the beginning of learning how to get out and be free of the dysfunction. And if this is what a family member is trying to "learn" and "practice" on to heal, yes, it could seem very strange and "out of character" to other family members, including "you".

That is what cognitive and behavioral therapies are meant for to help someone really learn what the dysfunctional buttons are and how to slowly learn "not" to respond to them.

Often the root of complex PTSD is from living in some kind of dysfunction
and having the wrong buttons pushed that constantly send the wrong messages which causes emotional challenges. A lot of visual and emotional flashbacks are expressing moments when the person was in duress where they didn't know how to react or defend themselves in some way.

OE