Of course, you have those select few people that will judge you for those mistakes no mater how big or small and hold it against you for what seems like eternity. However, we all make mistakes and have regrets, it's a part of life. Your friends need to be able to accept those mistakes as you have, and move on as well. If they're willing to hold mistakes you've made in your past against you, perhaps, they're really not true friends. This also goes for boyfriends/girlfriends. If that guy you like is going to hold a mistake/regret you made in your past against you as well, something you can't change, perhaps they aren't the one for you. Even though it may hurt for awhile, you must move on to someone who will accept those mistakes, regrets, and accept you for who you are instead of trying to change you and make you feel horrible for those mistakes you've made and have already overcome, but instead continually bring you down for those mistakes. Acceptance of those mistakes is a major priority, if you can accept your past mistakes and regrets, then other people will too.
(A blog with food for thought. :) )