Who is responsible for the accident repair and why?

I do not understand why you mention your friend; it does not seem he did anything to cause the windshield to be damaged. You need to supply additional information for us to decide liability. Since you hit the ball over the fence into a lot where cars were parked, initially it would seem you have fault. If the fence was high enough that a reasonable person and you would not believe it was a likelihood you would hit the ball over the fence, then you might not have any fault. But if it was short enough that it was foreseeable a batter could do so, then the car owner was also negligent in parking the car in a zone of danger. The shorter the fence, the more at fault both of you were. If the car owner could have parked in a safer area, the higher his degree of fault.

Who should be responsible? Did your buddy hit the ball? Perhaps God is responsible? Are you blaming the guy who legally parked?

Yes. Pay it and learn whatever you can from the experience.

It seems to me that the City should have a higher fence. Tell the car owner to file a claim with the City (There is a six month filing statute).

Probably not. The owner of the car took that risk when he or she parked there. Congratulations on the homerun! Good luck.

Don't worry about it. In Florida windshield repair is paid for by the car owner's insurance company with no deductible. The car's insurance will pay for 100% of it so the car owners shouldn't try to get you to pay for anything.