I need to know what the laws are in FL for leaving state with your child prior to divorce.?

One of my best friends is leaving her husband...due to emotional abuse that has been inflicted upon her and her 6 year old daughter (not the husbands biological child). The only way for her to get out of his home right now is to move back to NY and stay with her family, due to monetary issues. The couple has a 6month old son together...he doesn't help take care of this child and she is forced to raise this child on her own daily. Her husband will not let her leave with their son and is basically holding them hostage. I need to know what can and will happen if she were to up and leave for NY while he's at work this week. Can he just come take this baby from her? Could she end up losing custody in the long run? Could charges be pressed on her? Any suggestions of what she should do?