Instead of being ashamed of something you did in the past and really cannot change, change your focus to see how it's an example of where you have been, and how you've come all this way, that it was something you can now learn from and know the signs of what not to do, and who not to allow to hurt you. Always two sides to the coin and being ashamed of something that is gone and over only serves to stop you in your tracks or at the very least slow you down in your growth.