Why she push her own child? Why she leaving without her kids with that dad?

I'm pretty sure it was stated that the dad absolutely planned on sacrificing MC the moment Astrid woke up/recovered. She woke up and took the child at the highest risk of dying to safety. The dad wasn't going to kill his sons, so they were lower priority.

The push? Idk but Tan was acting weird so maybe there was some magic reason that hasn't been revealed yet or she didn't recognize her own son because he was a dog last she remembered?