You asked us, "what on earth do I do now?". I recommend you start another post and change your question to "how do I monetize millions of users?".

Give us a description of your market without revealing your business of course, customer profile (age, income, etc) , how much information you have on them (do you have emails? location? interests etc), and how much time they spend on your site.

I'm sure you'll get much more practical and useful advice from that thread on solving the problem rather than the commisseration here on your bad situation.