My mom wants to call CPS on my brother for saying he wanted to harm his baby

My brother has has a 5 month old daughter. She was conceived through rape. His ex girlfriend drugged him after he broke up with him and had sex with him. She got charged in court and that's ONLY because she had told someone what she did and was bragging about it over text. So she was charged and lost custody of the baby and birth and the baby came home to my brother. He was gonna put my niece up for adoption but decided to keep her. I breastfed my niece through pumping. I stopped breastfeeding my one year old and by then my mom was pushing for me to breastfeed my niece. My brother was only comfortable with pumped milk so that's what we did. The problem is I live 37 minutes away so he would be making that drive daily to get milk. He recently said he was just gonna put her on formula and I said that's fine. I'm kind of over pumping anyway. My mom is a breast is best person and was really pushing my brother to continue or get donor milk which my brother found giving his daughter a stranger's milk weird and that's his baby. That's fine. He put her on formula and my mom had been guilting him and is now threatening to call CPS on something my brother said MONTHS ago. When his daughter was two weeks old he was dealing with purple crying, trauma, and exhaustion. He messaged me and my mom in a group chat saying he was depressed and was thinking about hurting himself and his daughter. So I had my boyfriend drive me to my brother's house. He saw his doctor to get on antidepressants and is currently in therapy. He is doing better than he was before. Much better. But she kept text messages that were from months ago and using them to guilt my brother into letting me breastfeed his daughter. I tried telling my mom even if he wants me to I'm done pumping and my mom was like "Well then maybe CPS should know about him wanting to harm Ivy." I asked my mom "If you really thought he was a danger to Ivy why wait until he won't do what you want to say something?" She told me she's looking out for her granddaughters best interest. So now my brother is stressing out and idk how to help him.

@sweetie Ivy isn't my child. My brother said he's done with her having breast milk and if we give into this my mom will think she has complete control over how Ivy is parented. I honestly don't want to pump anymore and my brother is done with this which is his decision