Since you have not mentioned about the reason of separation from your husband and also about the attachment of the child with the father, it becomes little difficult to talk. However, since she is at a malleable age, it should not be very difficult for her to adjust to this new environment until and unless she is extremely hurt or affected by the separation. There will be teething problems that will have triumph over time. You will have to be very supportive but firm with her so that she does not take the sympathetic advantage of the situation. Every child knows basic good values and they are not taught they are learnt on their own so one just has to be a good example to them.