You’re allowed to trim anything back to your property line, otherwise the tree is theirs. They have no obligation to cut or trim anything for you other than the tree rotting or being dead and that must be determined by an arborist that they are under no obligation to pay for or schedule. It’s on you entirely. The exception to this is the power utility companys. They have been given the right to trim or cut down anything that they deem as a threat or unsafe to their property/investment aka the power lines. However, they will always trim back the absolute bare minimum or be incredibly conservative so as to not incur much cost or be sued.

Basically, MA laws are fucking stupid. We had an issue years ago where we had to fight against a neighbor across the street who had 10-15 trees that simply originated on the edge of their property but grew towards us. They wouldn’t cut their trees, spent years only cutting the beaches on their side to add more weight to our side, and they won’t let us cut them either even if we wanted to pay. Have lawyers in the fam and we tried everything but ended up having to settle to cut it back to the property line and eventually got them to agree that we’d take it a few feetback beyond that so it didn’t grow back quickly. But we ensured we did it in the worse way possible so their trees look like shit now since we took away most of the greenery. They’re left with tall stumps now since they wanted to be assholes.

If you have pictures of the rot then you may have a case if it’s very clear from the pics but generally you should have called an arborist and paid the $100-150 to have them give you an official assessment and then taken that to them to get them to cut them down. You’d have easily been able to get the courts to force them to remove those trees at their own cost or protect yourself if they refused since they’d be liable.