Can the OP tell us what's happened now that it's been 2 years?

Wishing you all the best with your family.

Welp, time to abort... jk, seriously though, how would you feel as a ten year old to some random woman walking in and trying to play 'mommy'?

Clearly violent and learning lots of bad stuff from her mom. Tell your husband and get that little brat some help. Also have a talk with the ex-wife.

My mother and father were married for 15 years. Over the course of that time my mother cheated on him 3x, that I was witness to, and proceeded to date one of them post divorce and then cheat on him. Eventually she remarried a man that she had known for roughly 6-8 months, all within 2 years of divorcing my father. My current step father, to put it bluntly is a closet pedophile, has made comments towards me, and my mother shrugs it off. His daughters already receive 10x what I do in support, and they are a disgrace to civilized society. Believe me I know where this kid is coming from. My advice to the OP, learn from my mothers mistakes, the girl doesn't want another baby to make her feel like she is insignificant. To you or her father. I reacted aggressively when I found out about their marriage, and may have thrown a knife or two at his kids(trust me they did worse). Keep her feelings in consideration, that was never afforded to me and would probably help her navigate this situation.

How is your child? Unless you got an abortion...

that's called attempted murder

Have you tried having her aborted? I know she's obviously walking around and talking due the threats but its never too late!