What can I do about a malicious Neighbor?

A neighbor has irritated me for 15 years. I have tried to get along with him over and over, and just when I think things are pretty good, bam!....another act of spite. Now I have had it! I am pursuing the law, however most of what he has done and continues to do is within the law. He has blocked my view of the lake entirely, front and side view. He is threatening to cut down the only tree on the property line so I can’t hang a bird feeder there. He has installed motion lights next to my bedroom windows, he is planning to move a shed out front of the only little view I have of seeing outside, other than the bedroom windows. He tells neighbors outrageous lies about me. I feel so beat up…I am considering leaving my lake home because of him, and yet I wanted to live here. I have known this neighbor for 30 years, we used to work together. We have lived beside each other for the last 15 year, and even though it’s been a struggle at times with him, I would have never thought he would go this far. All because I told him I had enough, and I didn’t want him to speak to me any more. Now I’m a reasonable person. a very giving person, I even gave him the shed he plans on blocking my other view with. I think he could also be dangerous. It’s so hard to take. I’m not even sure if the law can help me….What can I do viewers. I am so angry…......and I feel hopeless at this point! He is just a thorn in my side…..seems like everyday he has thought of another way to add to this misery. What can I do???? Please help!