You don't. Honestly I think I think that all you can ever do is encourage them and help them move on, but they still need you and at least where I come from (not America) you don't turn your kids away. You brought them into the world, your choice, not theirs.
I know that I may sound cold, and that I go against the popular way of life in America. But it was my choice to bring my daughter into this world, and I will be here for her till the day I die as I know that my parents would be.