A friend gave me their PS3 and assured me it was 100% mine, now they want it back!?

[Samantha]

I had expressed my intentions to buy a PS3, when my friend (not a close friend) just offered to give me their PS3. I made sure that he was completely sure and thanked him, he brought it to me during my shift at work, and I once again made sure that he wasn't having second thoughts and he assured me it was fine. I took it home and proceeded to buy 5 games (worth about $120) and start using it. I reset the system and personalized it and sent him a text thanking him once more. This was Tuesday, today (Wednesday) he sent me a Facebook message asking if I could use it until the end of spring break and then return it because his sister wanted it back. I obviously don't want to return it and I don't think that I should have to, especially after giving him 2 chances to back out before he physically gave it to me, and once again giving him one last chance to change his mind when he brought it to work. He reassured me it was mine and that he was totally ok with giving it to me, and left seemingly ok with his choice. I really need some help as to how to go about responding to his Facebook message and proceeding without losing him as a friend. Once again, I don't want to come across as rude, but it's not an option to give it back (I have invested a lot of my own money into this), but I don't know how to get that across to him. I just need some help responding to his out of line message and how to go about it in the most polite way possible. Please and thank you.
Thank you to all the wonderful responses, It was good to know I wasn't over reacting! I went the polite route and explained calmly to him about how much I had invested in it already, and how I had already given him many opportunities to turn back. Turns out his sister used his Facebook to send the message to pressure me into returning it! Immediately after I sent my polite response he replied saying he was very sorry about what she had sent and that I don't need to worry, the console is mine

[Elaina]

Tell him what you think. i agree which you, he can't do that. Make sure hoe knows that he can't do that but don't hurt his feelings. Hopefully his man enough to just say "fine"

[Atheist Programmer]

It's not his PS3 anymore, but if he insists then buy it from him. Problem solved.

Tell him you can't give it back but you can buy it from him.

That's why I rarely accept "gifts".

[Jonah]

Tell him everything that you did with it, like buying games and reseting the system, then ask him if his sister still wants it. He should probably feel a little guilty, but if he still wants it back, then you should. It's only a console, and I know it sounds corny, but is that worth more than a friendship? You can still sell the games somewhere.

[The Dark Knight]

Tell him no

[S.D.M]

Inform him of everything you done to it, and how much you invested in it. Also remind him that he said you could have it. If he still wants it back...offer to buy it for a little cash. Not too much, like a hundred bucks. Now at this point your being as nice as possible about not hurting his feeling, but your feeling matter here as well. You might have bad feeling toward him after this, so keep that in mind as well. If he still wants it back after he already confirmed giving it to you, reset the system again, keep your games, and give it back. You can always buy yourself a new ps3 so you can play your games. Clearly this person is not a true friend. What you should do if it comes to this point is up to you.

No one likes losing a friend, but a person can't let someone do something wrong to them. If they do there not a friend.

Good Luck!

[Jones]

Lol sell the games to gamestop you might get 2 bucks if youre lucky