Proof of the trade was done

Hi guys

I just have been scammed. Or.. I will have the answer on monday when I call PayPal.

So. I wanted to sell my knife and this guy added me. He sended the money through paypal and on the money'transfer, he wrote a note that said he traded a knife with me. So after I recieved the money, i traded him the knife (I have pictures of our steam chat and picture of the trade)

10 minutes later, I could see that he tried do pull back the money by creating a case on paypal.

So now I have to proof that he actualy got the knife.
Do you guys give me some help of what I should do and say to paypal?

Make a screenshot of your inventory history within steam (cut out your personal info that is in top right, ie: login name) and use that and the other screenshots to:
1. Report to Valve that he scams
2. make a report here on SR that he scams
3. Defend on Paypal.

Please be aware tho that paypal's policy explicitly excludes electronic items to be traded.

Thx for your answer, but I was hoping to the some help on the "Defend on Paypal part" How can i proof that he got the knife?

ty for information i will use it too if some will attempt to do this