Sorry to hear that Tim - but good that you're being true to yourself and getting out when it wasn't good for you. Many people stay way too long and waste years more of their lives. You're a smart cookie, mate.
As to what to do...
Firstly, ride more - you miss riding, and there's a mind-cleaning aspect to long rides!
Secondly - spend a few months being a manslut
Third - don't just hang around, existing, waiting for things to get better. You left for a reason. Things are already better. Now get out and do something you've been wanting to do for a while - take an 8 week interest course through community college - they're surprisingly cheap and you'll be absorbed in something new and interesting, which will distract you until you're used to living alone. Everyone has a list of "One day, I'd like to do...", so why not use this as an opportunity to try one of them?
Fourth - go out with your mates. Just a couple of beers at the pub while talking shit would be good, not a big piss-up.
Fifth - get hugs from your friends (more likely from the female friends, than the male ones!) as you may be missing the sudden stop in skin contact with another human (I'm not talking about sexual stuff - just touch)
Sixth - believe that the last 4.5 years were not a waste. You had some good times. And you learned stuff about yourself and what's important to you.
Seventh - come out to the track on Sunday and pit bitch for us
