I think your AH pride is hurt. I do not think you wrong in giving your parents the money. You should be proud that you could do that for your parents. Hold your head up high and proud of what you are doing. As for your parents offering to pay off the mortage do what you think is right.
Question would you AH known you gave your parents the money unless you told him. If not then I would not tell him about things that will just cause a fight later on.
Stop self doubting your decisions.