Ex momma drama

So after 10 years, and now that I'm pregnant with my fiancé and I first child, my fiance ex girlfriend decides to do a child support claim. She said it wasn't her that did the claim, it was the state. She applying for welfare and wants child support! But LISTEN to this ! The child is not even his, DNA test said my fiance not the father they did this DNA 10 years ago. So it's kinda weird she coming to us now 10 years later and now that I'm pregnant. The child only has his last name. He has nothing to do with the child. He hasn't been in that child life cause the child is not his. He clearly owe her nothing. Why is she doing this now that I'm pregnant. It's really stressful and it's ruining my pregnancy experience. She just bought a brand new car and wants to just stress me. She doesn't know who this child father is. And has 3 more babies she doesn't know who the dad are for them either! My mother in law is furious with her behavior, and doesn't want me to stress so much for the baby sake. What you guys think?