I find it so embarrassing and I'm not sure what to do. At nursery she is apparently fine, but whenever I take DD to playgroups or to friends with similar aged DC, she snatches off them, slaps them, pulls their hair, bites. I seriously can't leave her for any amount of time otherwise she will lash out (and by leave her, I mean sit on the couch in the same room, instead of directly next to her and other child on the floor). I've tried doing gentle hands and it worked for a while, now she will just slap and hair pull etc and then stroke them after, but it doesn't prevent her.
I'm at a loss and I feel so guilty because I think this is my fault as I allowed her dad to treat me like shit in front of her for so long, and she's probably just so used to seeing it.