I have feelings of resentment caring for my aging parents as they had a home in a warm state and left their elderly parents in my care.

Act don't react. Can you go deeper, and find out what kind of person you strive to be. Then act that way. You sound like a loving person racked by anger over the selfish mistreatment of you by your parents. I suggest a sit down adult to adult, not parent to child, conversation, about your anger. If it is not cleared up, and you are still angry, talk to a therapist before you do anything. Hate and rage will destroy you. Then if you still can't find it in your heart to take care of them, rest easy. Karma is a bitch, what goes around comes around. You put in your caregiving time with your grandmother, while they enjoyed their retirement. Explain to them that this your time to enjoy your life. You earned a little selfishness.

I so agree with what you say,I/we my husband and I have up everything to be here and take care of elderly parents,its been 3 long years,and counting,I actually am begining to hate myself now for all the awfull feelings of anger,resentment,I am feeling all day every day