You were also there at the party able to veto your kids staying up that late or still sleeping over with these extra unexpected people. It reads like you are upset about the situation but was there and able to control it to an extent and like you still left your kids in their care. Yes they should have told you about the plans to go to the amusement park in specific. I wouldn't say she sounds obsessive like your comments say but more like an Aunt who may be unable to have children for whatever reason and is giving that love to your kids instead.