Advice for Neighbor's Tree Ruining Our Lives

Does anyone know what we can do about our neighbor's huge 80-foot tall
tree directly next to the property line; at least half of the tree hangs
on our side.  

We are in a high wind area, frequently in excess of 60+ mph, always
blowing in the direction of our house, putting our house in danger of
the tree falling.

Presently the tree is "raining" sap and sap-laced particles that cover
our house, cars and all the walkways. Just walking in the back yard the
bottoms of our shoes are caked with it.

Our cars need to be washed several times a week or the sap bakes into
the paint. 

About 99% of all the leaves and sap and danger affects us and he
experiences almost none of it.

The tree was trimmed once about 5 years ago, but now the neighbor says
money is tight and he won't do it again, even though he stated he knows
it needs trimming.

Legally, what can we do?

Thanks for any advice - we are desperate!