Pending Selling acc but through middleman

Hey. I tried to sell this account I had posted, okay? The person tried to purchase it w/o doing middleman. I agreed to it, gave him the information, but I did not confirm the email change as I wanted to know if he actually sent the money. He sent a picture showing that he sent it, but the money wasn't in my PayPal whatsoever. He then got angry and stated to change the email w/o being understanding. The money did not show up in my account nor did I receive an email about money being sent to me whatsoever.
I want to know if we should confirm the email to the other person knowing the money is not in the account yet? I gave him access to the account so he knows I'm not messing around, but he still got angry. I told him politely to wait, but wasn't so keen on it. Screenshot by Lightshot -- Screenshot by Lightshot -- (the anime profile pic is me) so yeah basically, I said i dont want to do this sale, and took back my account. Please help me and show me how middleman works, and how its more safe.. I don't want to deal with people like the guy in the conversations.

 

Here's a simple guide
 [Simple Guide] Playerup Middleman Service - New Members Read This! - UPDATED | PlayerUp Accounts Marketplace. Player 2 Player Secure Platform.

 

@Joeyfar