WTF, dude? If I were your brother, sister, or dad, I would take a shit on your PS3. I don't think you're a bad person but it seems like your priorities are a little screwed up. These people are your family. Your brother may have done something (I'm not quite sure what) to make you two stop speaking but your time together is limited. One day, you're going to look back or he's going to look back and wonder why you were such dicks to each other. You should have let the man play your PS3. I'm not sure what circumstances forced him to buy his own (Play PS3 or a bomb would go off) but you could have saved him a few hundred dollars. For that, maybe he could have bought the family a new 32 inch shitty TV.
As for your sister, you should have let her play it, too. What's hard about FF7? My kid is 9 and she can play Blue Dragon. The game has a tutorial and it was the first RPG for a lot of people. Is your sister dim? If so, send her to my house to pick up the free candy that I hide in my bedroom. And what if it was too complicated for her? She would have found out on her own. You stopped someone from possibly enjoying one of the best RPG's ever.
As for your dad, if I were him, I'd go back in time about 15 years (I can do that, you know) and spank you a little more. Maybe his condition warranted your response--denying him the sugary goodness of a blueberry cheesecake. But eating it in front of him? That was low. He should've knocked that cake on the floor and said it was an involuntary action caused by his diabetes.
Nobody's an angel and I'm sure you have plenty of redeeming qualities. If these three things were the worst things you've done, you're actually a pretty decent guy--just a little bit of a dick. But you asked............