Just got back from a class. I think you are correct about low self esteem, and this guy worked it against her. They do that. My ex had convinced me over time that my family tolerated me because of their love for him!!!!
When I left with my infant son, it took me a long time to feel like a person again. The one thing I asked of my family, was that they never say anything negative about my son's father to my son. Basically, if you have nothing good to say, say nothing. So that is what they did.
My son grew up and has a relationship, though difficult, with his father. Many times he came to me and vented about the man. I listened, and would tell him, this is who your father is. He will not change. So, if you want him in your life, you know what the limitations are.
Early in my divorce, my ex would try to speak to me in the same demeaning and debasing way. I told him, calmly and without emotion, that would no longer be tolerated. I would hang up, if on the phone. If in person, I would shut the door on him. I also told him the police were aware of our situation, and one call they would be there pronto. He was more afraid of public exposure then anything.
We actually have a fairly cordial relationship now, it has been almost 40 years since our divorce.
Fortunately my son had a remarkable man come into his life when he was 5. My DH is the man that taught my son how to be a good man, husband and wonderful father, and he will tell you that.
if your daughter could get some much needed counseling to help her see that she is a valuable person, it would be so helpful. Of course, that would be her choice. I couldn't afford counseling, but knew I was so badly damaged that until I fixed myself, I would attract that same kind of man. I stayed single for a long time and worked on bettering myself and in the long run healing.