I do agree with willistuder. A note to the people concerned would be the thing to do! All of my works are copyrighted and have invisible watermarks. This is a service I pay for, because someone was uploading my works as you did. It is not a nice feeling, it's a violation on so many levels.
The unfortunate thing is with the apology, you're going to have to climb a little hill before regaining credibility. In other words, not just words.
I would like to know why you still have stolen works on your site at Deviant Art. You have at least one made by Sed and I don't know about the others. Actions speak volumes. Personally, I wish you good luck but I don't accept this apology.
http://towmaster.deviantart.com