My wife is 19 weeks pregnant and smoking pep spice how do i tell her to stop i care she dosnt help!!!!!?

She moved out but we are working on things she is a free bird and i have found out she started smoking spice ..... 4 months ago she was addixcted but she got off of it i tried to tell her to stop and she told me i wasnt her dad help shes pregnant and smoking saying she dosnt have a problem but i seen it before any advice please i need major help how do i sound caring but can bang the point acros s too maybe i just need prayer i dont know help