What should I do?

My husband and I have separated. We got into an altercation and he tried to take my newborn. He’s been gone for a week now & wants to see her but we are not on talking terms. I don’t trust him I feel he will try and take her again. He took his boys from their mom for four months. She had to file for joint custody. I’m not keeping her from me but in my heart I believe he will take her until we go to court & that can take a long time. I told him I’m breastfeeding to not take her & hes willing to switch her to formula just so he can have her. What should I do? Am I in the wrong?