after I read VA reversed law quoted here. You respond your neighbor with a nice letter allowing him to cut and provide him convienence (such as allowing him cut from your side....), then you are done with your job.
You want to overdo only if you have money to burn -- cutting a tree will cost thousands of $$$.
I would not give in a inch when it comes to dispute with neighbors. Only if you pose with atitude "don't mess up with me" then you can stand still.