Legal Question in Civil Litigation in Massachusetts

Re: tree fall

Probably, yes, although I have not verified this. If the base of the tree is clearly on your property, you are probably responsible for upkeep and maintenance of the limbs and branches reaching over into the neighbor's property. (If the neighbor cut your tree limbs back so none extended onto their yard, wouldn't you have expected him to consult you prior to significantly modifying the look and reach of "your tree"?)

You could ask the neighbor to agree to share the cost, if s/he has not objected to the part of the tree extending over his/her land, or cut back the parts extending over the property or asked you to do so. Perhaps the neighbor actually enjoys the benefit of the shade it provides. You might try to use these or similar factors to appeal to the neighbor's sense of fairness, but I think they have every right to refuse.

Also, I would call your insurance company again, paerhaps speak to a supervisor, and ask them to identify the language in the policy on which their denial of coverage is based. Unlikely to change the result, but there's no downside to asking.