Helpless, how about calling this neighbor and discussing the damages? Record the call. Maybe even an across the fence coversation could correct at least some of the issues (record that too just in case). No matter what, don't put yourself in harms way though and keep emotions out of it. Simply state the facts and ask him how he is going to correct the damages. Having a recording may help in taking further action if he doesn't do the right thing but he is your neighbor and you should give him the opportunity to make peace.
The recordings could make a good background track on a video posted on youtube with a link emailed to everyone that could help.
