Let me just say that this was not 'just a mailbox'. This was around 10 mailboxes, and a fridge, and who knows how much more. On top of that, how much do you have to beat on a fridge to DESTROY it? Not to mention the fact that mail and bits of the boxes were flying because of how violently they were beating on them! Just think of they were spooked by OP yelling at them and they turned it on her! They were obviously violent enough to scare OP into hiding and fearing for her safety!
At any rate, whether it'll 'ruin their lives' or not, they should have known it was wrong and they should have known there would be consequences if they were caught. Just because they're 'just kids' (though three were 18) doesn't mean they get a pass on comitting a crime in such a violent way. They should have known better than to do it in the first place and so they should be punished accordingly. I say press charges and if you're worried about them taking out some revenge, keep a gun handy by your bed or by the door, somewhere that's easy access for you.
By the way, I'm 20 as of a few days ago, I was 18 not too long ago, and even before that I knew better than to vandalize others' property or even my parents' / my own property. It isn't right no matter who owns it, no matter what your age is, no matter who your friends are, no matter what your last name is. That's common sense at that age (even for the 14yo).