OP, do you have insurance? You know that is what insurance is for, right?
In addition, it is a reputable property attorney you need, not a real estate attorney. My friend has tons of outstanding, top notch (truly), high paid attorneys (she's rich), and she has at least one property attorney. I can ask her the name. I am somehow sure they would get things done, if you know what I mean. How much are you willing to pay?
An arborist is definitely insufficient. Photos alone MAY be insufficient. You have to take them a certain way, showing certain information.