Hi fernan, Welcome to WebmasterWorld! [webmasterworld.com]
To deal with the competitor who copied your content, write and send an immediate cease & desist (C&D) letter to the infringer. Search for email addresses on the site, and in whois, and send a cc to all you can find. Be sure to include the time/date you expect the content to be removed by (usually 48-72 hours if you email the C&D, or 10-14 days if you decide to snail mail it), and that if it is not removed, you will take further action against him/her.
If the infringer doesn't remove it, contact the host. There are many hosts that will remove the content (and often the entire site) as it goes against the TOS the hosting client agreed to when signing up, and they don't want to find themselves on the receiving end of a lawsuit because of something a client did.
You can find many sample cease and desist letters online.
Here are some other threads on copyright infringement as well:
As for the AV part of the question, I am not sure about getting it back into the index if it has been banned. Hopefully an AV expert will post some information to help you with that aspect of the problem.