Definitely vent here instead of engaging with her. I agree with others who see this as baiting for a response. Keep in mind a narcissist likes to create drama because it gives them a sense of power.

They are USERS and will use anything they can think of to create drama, then they get to play the victim. Yes, they look for a way to triangulate by pulling another individual into the conflict. This includes even their own children.

You are new to this yet you are actually intelligent because you are realizing the importance of not reacting.

Good idea going to the bank to ask what you can do to change the way this account works. The key is to set something else up that only you can access. Pretty sure they can help you do just that.