To what extent should I accept my friend's decision?

My friend is being manipulated by her husband. Her husband wants a son and only one son and she told me that she promised her husband that she will have an abortion if it turns out a girl. Her husband is old money and does not want a girl because they don't carry on the family name. I find this outrageous and even more so after I heard my friend agree with it. Would it be rude of me to criticize her on this decision?