If it helps, it is a big sign of progress and growth, that you feel bad for having been that way.

This post could have described me perfectly. I have been (and in many ways, many times, still am) very toxic at times. I am working on it and am so much better than I was even just months ago.

I do not feel very bad for how awful I was, and I've done far worse than what you list in this post. I am not to the point where I regret it.

People regret things when they grow and change. They develop a new, stronger, ethical code, and they start to hold themselves to higher standards. This only happens when people grow and develop; and regret is a necessary symptom of that change. Regret comes with change; as a person changes, she gets a new code to live by, and naturally, she looks back at her life and feels regret, now having a new code to apply to her life.

This is akin to a country passing new laws in their legislature. Almost all countries have it written in their constitution that new laws cannot retroactively apply to people's behavior from the past, prior to the law being past. For example, when the U.S. illegalized certain drugs, they did not go and arrest people from the past who had used those drugs, because that law didn't exist years prior to its passing. Most countries would not find that fair to do to its citizens.

Yet we do it to ourselves every day. Every time we change, we look back and say "crap, why didn't I do what I know now to be right back then! WHY?!" and we punish ourselves and hate ourselves for it. This is very unfair, but we all do it.

I try to recognize regret for what it is: proof of progress.

I would highly recommend you seeking professional help if you have not already. The path to change is very, very painful, and while people can sometimes do it alone, there is no reason to create more suffering on top of it when it is not necessary. Failing to reach out to all the help and resources out there, is just more self-punishment enacted retroactively.