Nothing will launch, can't turn off computer

Hi there. I'm on a MacBook Pro running OSX 10.9.5 with 2.5GHz Intel Core i5 and 8 GB 1600 MHz DDR3. I downloaded an app called BitTorrent a long time ago, and I forget why or even what it does, so I haven't used it in over a year, but it came back to my dock yesterday and I couldn't close it, even with force quit. I tried terminal "KillAll Dock" and it killed everything but that. I looked for BitTorrent in Activity Monitor, but it wasn't there. I tried logging out, but then the problems began. It just wouldn't log out, no matter how long I waited, so I went to turn off the computer with the power button, but it gave me a message saying the computer was already logging out, with no option other than to accept. Now, whenever I try to open any app, and I mean every app (Terminal, Safari, System Preferences, etc.), it seems to open for just a second because I see it highlighted in the dock and then it closes immediately. The only thing still technically "open" is BitTorrent, which is completely unresponsive to anything. I've tried closing the laptop and opening again, and I log in but to the same situation. Please help!