Just got scammed...

Hello guys...just got scammed. Could someone tell me what to do and where i should turn to?
Here's the scammer's profile: LINK TO PROFILE He uses the name of a man with which i contacted and he said that he was not using his ST profile from a long time..

Never tell your password to anyone.

Ninj??Sty??e?: Yes?

KaSTiEeL: hello you have 2k collection?

Ninj??Sty??e?: Sure i do have it

KaSTiEeL: are those steam keys or gifts?

Ninj??Sty??e?: Keys

Ninj??Sty??e?: Thats what it includes:

Ninj??Sty??e?:

-Borderlands 2

-XCOM Enemy Unknown

-Civilization V

-BioShock Infinite

KaSTiEeL: how much is paypal price?

KaSTiEeL: by the way i have bioshock infinite this might be a problem ya?

Ninj??Sty??e?: 15 euros.

Ninj??Sty??e?: I think you will receive it as gift

KaSTiEeL: well thats ok then give me your paypal email and the key

KaSTiEeL: once i activate it you will get your money

Ninj??Sty??e?: Not again.

Ninj??Sty??e?: I have more rep than you, dont i?

KaSTiEeL: i have +173 rep and -2rep

Ninj??Sty??e?: on steamtrades?

KaSTiEeL: yeah

Ninj??Sty??e?: could you provide a link

KaSTiEeL: sure

Ninj??Sty??e?: because you didnt post on my tread.

KaSTiEeL: yeah

KaSTiEeL: http://www.steamtrades.com/user/KaSTiEeL

Ninj??Sty??e?: Okay. Thank you. Sorry about the argue. Just had to.

Ninj??Sty??e?: So here's the paypal email: joantasov@gmail.com

Ninj??Sty??e?: and wait a second to give you the key

KaSTiEeL: ok waiting

KaSTiEeL: you got the key?

Ninj??Sty??e?: Yeah

KaSTiEeL: ok give me the key once i activate it you will get your payment

KaSTiEeL: you dont have key do you?

Ninj??Sty??e?: Here they come.

KaSTiEeL: ok

Ninj??Sty??e?: Bioshock's one: *Not showing you guys*

Ninj??Sty??e?: Borderlands 2: *Not showing you guys*

Ninj??Sty??e?: I think that's CIV5: *Not showing you guys*

Ninj??Sty??e?: XCOM: *Not Showing you guys*

KaSTiEeL: ok activating them

Ninj??Sty??e?: Tell me when you are ready.

KaSTiEeL: bioshock didnt activate

KaSTiEeL: how much is witout bioshock

Ninj??Sty??e?: Dude

Ninj??Sty??e?: i see you have it in your inventory.

Ninj??Sty??e?: Just dont try to scam me.

KaSTiEeL: i told you i already have it

KaSTiEeL: oh

KaSTiEeL: so it came to my inventory?

Ninj??Sty??e?: did it?

KaSTiEeL: checking

Ninj??Sty??e?: Nope it didnt

Ninj??Sty??e?: Well then you have it as a key

KaSTiEeL: ok

KaSTiEeL: promise me you wont use

Ninj??Sty??e?: Why would i bother to use it.

KaSTiEeL: ok write your paypal again please

Ninj??Sty??e?: joantasov@gmail.com

KaSTiEeL: ok sending in a min

KaSTiEeL is now Offline.