Unfortunately at some point she might need tough love (your saying that the baby is in jeopardy and that you will take steps to protect him). It would be good for her own sake to write down what she said in the past so that you can refer her to it later (that she said that he brainwashed her, that she said that he yelled at the baby). Then next time she starts defending him, you can show her her own words. But for that they need to be written down. Or, recorded as an audio, which is better but hard to arrange. What I am trying to say here is that instead of your trying to MAKE her SEE THAT, you would rather REFER HER BACK TO WHAT SHE HERSELF SAID.