Those boys went beyond normal "boys will be boys" behavior
Some mess is to be expected, but for them to do the destruction they did, OMG!!!!!! I have FOUR boys and they NEVER were allowed to run amok like that. How are your walls, I bet you'll need to scrub them, and hopefully won't need to repaint.
Definitely talk to them about this. Who cares if they are friends of your best friend, I bet she'd go off on them too if you told her what went on. Disgustingly poor parenting, and I'm sorry that you have to clean up the aftermath
