Hi John,
If they were doing articles and promoting them then this is why your website has been hit. Article websites took a major hit in the update prior to Christmas and the Penguin 2.0 update last night has more than likely reaffirmed any penalty you were going to receive unfortunately. Do a backlink analysis in OSE and find all the article websites with links on and get them taken down (if you can, obviously if you have login details then this will be easier). If you can't then use the disavow tool.
Don't forget that any onsite changes that you make, you will have to wait for Google to come back and cache the website before you see any effect. Concentrate on creating great content and look to create relationships with those in your industry and concentrate on your outreach. 5 links on relevant, topical blogs are worth a million times more than 10000 links on article websites.