PayPal Chargeback Fraud – Please help!

This nightmare continues after all:

Beware + A Chargeback Fraud -UPDATE IMPORTANT UPDATE- 17feb at 8UTC
THEY have seen my journal on the deviantart, i even got a Screenshot of it over mail, and claim that there was no blackmail!
(While at the same time they require me to sell every art concept at the same price at which they bought it for the past 2 months in order to gain $4800. That is impossible!!! Because according to this, I should sell each concept for more than $100 per piece! Not my fault they pounded out prices, it was an AUCTION! Not flat sales!)
I GOT A NEW MAIL
So yeah, after explaining that it might not be HARD blackmailing, it is still a kind of blackmail while at the same time they expect me, although I have already told them tha

I am devastated.

Although we reached an agreement, (he wont do chargebacks and i will resell concepts) and I did my part of the deal and helped him sell the majority of the purchased works.

This morning (3AM) i just received notification from paypal, that few of my transaction from *HIM* got chargeback, which means, as you know all the funds i received for doing the artwork is taken back by paypal issued by the person who bought them. Some of these transactions date four months back!
What's worse, than being backstabbed, is Paypal already has disabled my account two days ago and on top of that is going to hit me with 20$ fee per reversed transaction.
My account is already in the minus - RED.
And judging by earlier statements by him, he made a chargeback for EVERY single transaction. Which means that the new chargebacks will occur and my account will fall into even greater dept and negative balance.

Please.. help..I dont know what to do...

https://www.paypal.me/northernredart