Even if what Angela says is true - that SK is responsible for little Elaina's injuries, and even if it's true that SK (or whomever "they" are) threatened her if she told anyone, it DOES NOT excuse her not calling 911. It's a mother's duty to protect their child(ren).
Given the lies Angela has told that have been posted on twitter (she said she thought the baby had been sold for drug money, she said "If I had something to do with it, why would I be out here?" - all the while knowing exactly what happened), I'm having a real hard time believing anything she says, especially with her history of child abuse (that's been posted here by verified insider Ferretmommy).
Oh - and according to JK, Angela also lied to her when she said she had no place to stay Saturday night, June 1, and asked to stay @ JK's house.
At this point, I'm equally suspicious of both Angela and SK.