I wouldn't keep a notebook as it focuses on her negativity and gives her more power over you. I'd ignore as best I could, but I also wouldn't let anyone spray my dog with water - what's next?
Take her wind out of your sails and you decide what you and your DH want to do - that way you are both happy. I don't think you "have to"" visit them - use your upcoming move as an excuse; you're just far too busy with the tree!