Well firstly I suppose the most productive way you can spend copious free time asides from learning a skill of some kind that may be valuable in future employment is reading. In fact, it may not even be that 'productive', but it gives you a new outlook on things and is still, in my opinion, the best method of escapism there is.
I mean, listen, I've never been in your position, so I can't possibly understand what it's like to *live* like that, but the reasoning, the pessimism, the creeping misanthropy that grows with every passing day and the impression of futility you have towards every endeavour I understand all too well.
I'm sitting here in my apartment, I'm effectively done with my degree now. I live with 2 other flatmates, both of whom are out drinking and partying, and all I want to do is go home... That's it, just get on a plane and go home and play MGS4. Im tired of this damn life, the last damn 3 years. I'm also exasperated at how everyone always told me at how 'great' university was, what an awesome time I'd have partying.
I'm tired of that shit. University has been nothing but a means to an end that I now will probably never follow. I guess my main advice to you would be to pursue something you like in an environment that is beneficial to you, because university these days it seems, on both sides of the atlantic, is simply non-stop partying for 3 - 4 years. I mean, I'm looking back now just fucking wondering how the hell I managed to get through it all.
What's worse is the bitter taste it's left in my mouth will probably fill me with pessimism for the rest of my life. It's sapped me of all desire to work, to start climbing the 'greast pole' of a career. It's just mind numbing...