Scammed on eBay/PayPal. What do I do?

Hello, I'll make this as short as possible. I've been using PayPal and eBay for the last 5 years. I've had 0 problems selling on eBay until now. This is my first very large sale and I live in the United States.

Anyways, I sold some items for $4,250 to a buyer in the US I made sure to get tracking and sent the items to him. I then transfered the money to my bank account and paid my mortgage and a few other bills. Well a few weeks later he files a claim with PayPal saying the items I sent him weren't correct and he wants a refund. So I responded to the claim and told him to ship the items that I sent him back to me. He provided tracking information and it arrived to me a week later. So here's the problem, he sent me back a bunch of crap that I didn't sell to him. So I refused a refund and PayPal automatically sided with the buyer. I explained to a PayPal representative on the phone exactly what happened and she didn't seem to care. Now my PayPal balance is over $4,000 negative.
What do I do now? Paypal pretty much just let him scam me! Will I go to jail if I don't pay PayPal back? What can they do? Please Help!
Added (1). I would also like to add that I sent PayPal pictures of the wrong items that were returned but it didn't make a difference. I also mentioned that the weight of the package was off by a couple pounds but the PayPal representative kinda chuckled and said it didn't matter. I'm mainly concerned that I'll get sued or go to jail. I'm not sure what the police can do if I were to contact his local PD. It's pretty much my word against his at this point. I will never use eBay or Paypal again.

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