My iphone is in lost mode after trying to sell it to a (shady) buy

Hi, my name's Dave from Kenya and I'm in panic mode right now. I have an iphone 6 plus 128GB that I was trying to sell online through a site that's like ebay here. So I got a interested buyer, invited him to my house and let him check out the phone before he bought though One mistake I did and regret badly is when i signed out of my icloud (which disabled find my iphone) and let him use it to check if every part of the phone is working well, both software/hardware. After he checked everything and found the phone was in good condition, we went to a bank to cashout his payment so that I may officialy hand him the phone and little did i know that he signed into his own iCloud on the phone and enabled find my iphone using his account.

He came to my place via uber and we took it and drove to a "specific" bank he insisted to cash out on and the odd part was where we were i couldn't see any bank at all. Anyway, while we we got there, he insisted that he goes with the phone inside the said bank and then he'll come back with the payment. Obviously I refused cause I've heard so many cases where people get conned and the supposed buyer gets away with the phone.

So we waited for him in the car with the uber driver for almost 20 minutes until the driver called him in which he answered and said that he'll be here shortly. We waited for another 20 minutes to no avail. He calls him again and he won't answer the phone, even switched it off. I felt bad cause not only is he a con but the guy left the uber driver without even paying him.

So when I got back home and when my phone connected back to my Wi-Fi the found my iPhone sound started ringing and now the phone is in lost mode. I'm really worried cause what if he says that its stolen and I somehow get in legal trouble?

When i log into my icloud, my phone is still in there with all its details except the number which is now changed to his. Is there any help I can get with this cause my iPhone was heavily involved with the online work I was doing with.

(Ive sent this via my sisters phone afteer calling her using a neighbors phone)