I don't know what you've done, Renounced, but I don't believe you're a bad person. When someone is looking hard at their behavior, recognizing where they went wrong, and working to improve, that's not bad. Perhaps you've done "bad" things. Perhaps you've hurt people. These acts alone don't define you. What you do in response does.

You say you want to apologize. An apology can't change what's been done, but if it's appropriate--ie the person you're apologizing to is still speaking to you and is not frightened or angered by any contact--an apology will go a long way towards healing.

This is meant for kids, but I've found this incredibly useful as an adult as well: A Better Way to Say Sorry from cuppacocoa dot com

I'm sorry for... [Be specific. Show the person you're apologizing to that you understand what they are upset about. This is about how they've been hurt, not your feelings and guilt.]
This is wrong because… [This is one of the most important parts and will take some thinking. You need to understand what hurt them and why. Again, this is about empathizing with how they feel and not just whatever guilty feelings depression might be sparking.]
In the future, I will… [Positive language! Say what you're going to do, not what you won't do.]
Will you forgive me? [They don't have to forgive you. They may not. Accept that. But if you want to reconcile, asking for forgiveness is necessary. However they respond, respect it. If they say they forgive you, they've forgiven you. Don't make it harder on them by continuing to try to assuage your guilt!]

Whether they accept your apology or not, remember what you've promised to do in the future to avoid causing hurt. Try to stick to that, while recognizing you're human and may continue to stumble and make mistakes. Forgive yourself as well.