“Her: Make sure your tattoo is covered. Tattoos look dirty with a white dress. You sister is thinking of getting a tattoo. I told her she’d regret it. Imagine how yours are going to look in your wedding photos. Terrible.”

You know, you ARE allowed to disinvite people whose behavior is unacceptable. And that behavior (basically plotting in advance and over the long term to take over your wedding for her purposes) is really unacceptable.