Mandy, You have a heart and the compassion shines through. I think it's wonderful that you are still seeing the aunt and doing things for her. She's no longer able to do them herself and god forbid, your x and his wife can't find their way out of a wet paper bag with a flashlight, to come to her aid.
Some day, karma will bite them in the butt and they will be in the same position and will require tending to.
My hat's off to you for being the person you are!
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.