The positive in this picture is that you remained calm during the time where you had to sit across from her. Good for you, good for you to realize that the time you have been away from her you gained some personal clarity.
Now, that you have made it past just being in her presence, yes, the symptoms of PTSD can become a challenge again. However, truth is you can never change "her" the only one you can work on is yourself and that is what is important. Is "she passive agressive, is she narcissistic?", that usually means that someone did not develop correctly, that someone probably got hurt, maybe she was neglected, abandoned and her behavior is her only way she knows how to "self protect". You are leaving her, so in that for her, she is being abandoned again so she will most likely look to punish you if she can because that is the only thing that she can gain a sense of self empowerment from.
Feel sorry for her, pray that she finds a way to get help. As for you? Do not let her hand you any sticks that you beat yourself up with. You have to continue to distance and work on your own healing and slowly learn how not to grab the sticks that others may try to hand you to beat yourself up with. That is HARD to learn how to do when struggling with PTSD. You have triggers that you need to identify and understand, often these triggers will be reminders of people and situations where you were handed sticks that you grabbed onto and beat yourself with unknowingly, often these sticks get handed out to individuals who unknowingly grab onto them, and often those who hand out these sticks have a sense of who they can push these sticks onto. For these individuals?, they foolishly gain a sense of "empowerment" from punishing others. They do not see "you" but only tend to see themselves, their own needs and sense of empowerment/authority/sense of superiority, even when what they are doing can hurt others.
Be proud that you did well, if this person is as dysfunctional as you are describing, you made the right choice.