Oh, look at that, all my clothes are in the pool.I was hoping to go swimming anyway.Thanks, Grandmother dear!?

Not sure if you are saying she put your clothes in the pool or not but there is not much you can do if your parents invited her to live with them. Or are they living with her? Either way you are correct in realizing that only when you are old enough can you move out and have peace. it looks bad, even if justified, to defy her, a frail old woman. I would suggest you stay away as much as possible from her. Im sorry you have to grow up that way but it certainly is motivation to study hard in school to get good grades, get into a good college and then a good job to make enough money to have your own place where there will be no one to put your clothes into a pool. Best wishes