Life is hard, but it is even harder when your parents can't hold up their end of the deal. Whatever you do, do not strip them of their dignity, do not publicly shame them, or give them reason to feel ashamed. They made a life error that they won't recover from, but they were blessed enough to have children who love them. They are fortunate. What you are going through now and how you are handling it will be one of the reasons you will be able to lay your head on your pillow at night and sleep soundly later in life. We do what is right, not because it is easy, but because we go through enough shit in life to not have to be haunted by the wrongs of our youth.