I am so sorry you have to deal with this..

It was extremely unethical of her to promise you that she'd be seeing you after retirement. I think, it was also unethical of her to conduct therapy in such a manner that she was acting more like a mother towards you than a professional regardless of how much you liked it and how much you felt it was helping you.

She was supposed to understand your vulnerable position and how her actions would create unrealistic hopes and expectations in you that could cause you trauma later, which is exactly what's happening right now. You are traumatized because of her careless, irresponsible, unprofessional action.

You do have the right to sue her or to report her to the board or both. I do want to say that pursuing legal actions is a very emotionally challenging process for a traumatized person to go through. So, take a realistic assessment of whether going through it would be healing or more traumatizing.