It doesn’t matter how you’ve behaved, what you’ve done, or what has compelled you to apologize. Whatever has made you want to apologize, I’m all for it. Following is the apology instruction manual:
You say, “I’m sorry.” You can add, “I’ll try to do better in the future.” This isn’t necessary, but helps a lot, because when you let go of the past, it’s always nice to hint at a brighter future. And then you say… nothing. Don’t explain it. Don’t complicate it. Don’t qualify it. Any more words and you only risk saying something that will dilute it. As Ben Franklin said, “Never ruin an apology with an excuse.”
Finally, when it comes to apologizing, the soundest advice I can give you is to get in and get out as quickly as possible. The sooner you get the apology over with, the sooner you can move onto telling the world you are going to change.