I would have to say avoid her as best as you can and then treat her with kindness, why stoop to her level and give her something to back up her claims. I most def agree with the post that says "This is her battle, not yours. Sheild yourself as best you can,...". Since you had a positive experience with your stepson and his family....focus on them! who know maybe the step daughter will change the anger and hate inside and want some of she has been missing out on with her brother, stepmom and dad.