This crash wasn't your fault, you just didn't avoid it as effectively as you could have done when things started to go wrong - you probably did better than most people could.

If you want to look for a safety improvement (other than not riding side by side and hitting your brakes when you saw the guy, which would have given your friend room to swerve - and with the right tyres you could stop the bike in a couple of times its own legth at 15mph) then wider tyres would have helped a lot. Good ones would probably be faster too, except in very specific circumstances that have nothing to do with transportation and even less to do with fat bar hybrids:

Tech FAQ: Seriously, wider tires have lower rolling resistance than their narrower brethren - VeloNews.com

People run 25mm tyres on hybrids because "They do it on the Tour." But often pro road racers go up to 28s, and they ride in a more aero rather than rolling resistance dominated speed zone . And, oh yes, because they are racing.

As for getting back on the bike after a serious injury of a near fatal... It's entirely personal. You should be no shame or pressure if you don't want to. Get back on the bike if and when you feel the desire. Something that might help rationally is knowing that with practice - and better rubber - you would have been able to brake out of the way of your friend instead of swerving:

http://sheldonbrown.com/brandt/over-the-bars.html

http://sheldonbrown.com/brakturn.html

But mostly - just stop being so hard on yourself.