Mex scammed(tricked) me

Hello i want to report Helper named Mex .
So here is the story .
On 2rd of July me and Mex made a deal. The deal was : I will send him 10 euros on steam ( with code which i gave irl money to get it from machine called PayNet) and he will give me 10 euros on Gta-Mp.cz. I donated and got that code. Sent it to him and it was working well . He got those euros on steam and i asked him to send me the money on web now. He said that he want to donate first and later he will send them . So i waited 1 day . After some time i asked him where are my money and he told me that he dont have enough money on paypal to donate . So i waited some time again . I asked him the same question again and this time he told me that he have limit . I told him to request limit increase and he told me that he already did that (i am petty sure that noone have limit on the 3th day of the month + check the donation email please ). I asked him why we need to wait that much ? . Simply send me ingame money ( he have 200m ) and donate for your self later . His answer was : I dont wanna spend my ingame money . And i told him : You wont just send me money now and when you will donate you will get them back + you can even make some profit ( since i asked him to send them with the lowest price per 0.25 usd ingame on s2) . He just left. The next day or so he downloaded cs go and had problem with it . I think his pc dosent support it . And i tried to get some answers on google to help him . But he requested refund (his request is accepted but he still dont have the money back ) .I said ok but when i will get my usd ? He said sell me an item on steam for 10 euros i will buy it . And here the problem actually starts . I said wait ... I dont want money on steam . I want money on Gta-mp.cz . And he told  me that he wont give me money since his game was not working . And i said : Man wait , if i wanted money on steam i was going to donate for myself not for you ... . I gave irl money for you and now you simply dont want them ? We had a deal . So i said that he tricked me and he sent me this message : Mex: OK NEXT TIME YOU WON'T DONATE FOR YOUR SELF JUST SPEND THE 11USD (even if i dont get it much) . I said : IchBinIwAn: well i have nothing with your problem . IchBinIwAn: ask steam/buy new pc/ or play from your friends pc.
Here we stopped talking .
And one more thing . We made a deal . The reason why i trusted him in all these things is that he is my friend since 2014 and he is helper. Now he is like " wew my game isnt working who care i didnt gave money for it" . I also cant refund my money cuz PayNet generate only codes and its something like public ATM . Since you cant check chatlogs on steam we dont have much conversation on web . But still there is enough just to prove that this is real !!!
Thanks for your time !