Can I sue my Neighbor for defamation?

I own a construction company, 25+ years commercial/residential work. I put an addition on a house I own. From the day I began to clear trees, the neighbor has harassed me. They called codes repeatedly about a non-existent water issue among other things, never received a violation on anything. They called police repeatedly, never received any citation. They called/wrote Town Supervisor and Highway superintendent claiming I was doing “below standard work” and “doing work without following Town codes.” They wrote the assessor and said our property Is damaging theirs they want a reduction in their taxes, and the Town did, with no proof, no evidence. I have a 2016 letter from an engineer that states I am not. She wrote a letter to the Town Justice falsely stating I am ruining their property with water and my actions, she told the lady answering the phone the story. They are disparaging my business/name all over the Town I work in w people I do business with for years emails/calls