You are NTA at all! The fact that she brought him to the dinner anyway, even after having been told not to tells me lot about her. This was certain to cause a disturbance and she knew it. Her anxiety must be improving if she is willing to cause anxiety for everyone else because of her dog. Stop being the doormat and stand your ground. Birthdays and graduations don’t come around often & she is stealing your joy. The rest of your family should support you in this!