Careful with being sue happy. It sounds like you raised a property line issue, and these people are responding by trying to clear your side of their stuff. It sounds like you are overreacting to the change this is incurring (what trees are cut, etc).

Chill out, put up the fence, keep your blinds drawn and wait a few months without interacting with them. Focus on watching a good TV show. Then go into your backyard and start replanting in a way you like. Life is too short to squabble over some bushes. Once the good fence is up, the neighbors won’t really be able to come onto your side. Good fences make good neighbors and all that.