stressed and confused.

My baby's father has a new girlfriend that he's moving in with only two months after knowing her. We had been together for 3 years and I'll be 30 weeks at the end of this week. He insists that he'll be there for me... but that he wants this other person in his and the baby's life too. I told him that I don't want her to be a part of my daughter's life. Just stressed and confused. What would you do?