you have to assure her that she is loved very much and that the baby is by no means taking her place. try to involve her in taking care of the baby like helping with preparing the bottle and so on if she feels involved she is less likely to want to hurt him. please don't do anything drastic if she realise that you are thinking of sending her away she will think you'll love the baby more than you love her. be sure that your new partner sends the same message. hope i was of help