The article 7 Tips for Communicating with Your Children About Your Divorce is a wonderful guide to how to talk with your children about your divorce. It is key that both parents are together when speaking with the children. I would add that determining whether you speak with each child separately or not would depend on the personalities of your children. If one child’s reaction would increase the anxiety of the other, then both parents may want to speak with each child individually.
Remember to not blame the other parent. Your children love both of you. You only need to give them the age appropriate information they need to process this life transition. It is helpful to seek professional advice in order to be sure that you are explaining in the best way possible always mindful of your children’s best interests.