Shuck

Last week I was on my way home and decided since no one else was on the road for miles and it was a smooth straight road I would take the T/A up in the speedo. Well I got going and decided that I was going fast enough I let off the gas when I did I felt a pop sort of and pushed my clutch pedal in and took it out of gear, the clutch pedal came up slow at first and then when I pushed it back down and let it up it was fine. Well I was driving on the interstate and I noticed at any speed above 60mph I let off the gas there is this shake or vibration until I get back on the gas. I jacked the car up today and noticed on the passenger side there was tranny fluid on the ground and underneth my car. I looked and it seems like it is coming from where the drive shaft goes in the tranny but I am not 100% sure on that. Does anyone know what I could have done? Any help would be appreciated, thanks.