"Ask God for forgiveness. Seek forgiveness from those you have wronged. Forgive those who have wronged you. Forgive yourself."
Elder Grow gave a great talk about the Atonement, and about how (with the exception of sins of perdition) every sin can be forgiven and overcome through the Atonement of Jesus Christ. It's never too late, in this life, turn back to God, and to change. I love that.
The part that stuck out to me most was the part I quoted above. I have come, and am coming, to find out that forgiveness is freeing. Take care of it, then just let it go. God doesn't want us to beat ourselves or each other up about things that have happened. Take it to Him, do what He asks, and move on - believing that when He says you're forgiven, you are.
Experience freedom. Forgive and be forgiven.
It works! =)
(Read the rest of the talk here: http://lds.org/general-conference/2011/04/the-miracle-of-the-atonement?lang=eng )