Often, the right thing to do in life isn't necessarily the easy thing to do -- and this is true in your situation. Yes, it would be easier just to do nothing -- but it would be wrong, and your feelings of failure and guilt would hang over you the rest of your life.
But don't just think of yourself; think especially of those you've hurt. Your letter doesn't go into detail, but how would you feel if you were a child whose father had walked out on him? How would you feel if you were a wife and mother who only knew heartache and betrayal, and finally abandonment, from her husband? I don't know if these describe you exactly, but from what you say, your legacy hasn't been any better.
What should you do? My prayer is that you will first of all turn to Jesus Christ and commit your life to Him. You need God's forgiveness, and You need His strength to live the way you should. The Bible's promise is for you: "Everyone who believes in him (Christ) receives forgiveness of sins through his name" (Acts 10:43).
Then ask God to give you the courage to tell those you've hurt that you know you were wrong, and you want their forgiveness. It won't be easy, and some may reject you, but it's the right thing to do, and it can bring healing -- both to you and to those you've hurt.