First off, be as honest as you can with your children. They don't need to know all of the dirty details about the divorce, but they need to know that daddy isn't coming back. You need to reiterate that no matter what happens, you will always love them and be there for them. When my former husband and I divorced, it was hard; one night my daughter was crying because she wanted him. The hardest thing I had to do was go into her room and tell her to look around. I told her that her dad and I were divorced, that he wasn't coming back, and that we (me and her) were now a family unit. It may sound harsh, but she got it.
I would also recommend talking to her school and daycare (if he/she is in one). They need to be kept abreast of what is going on. Know that eventually your children (those who are at the age to remember, especially the 8 yr. old) will eventually act out because of the divorce. When I divorced, my daughter was 5 yrs. old. She did pretty well in kindergarten, first, and second grade. In third grade, it was a different story. She saw other kids with fathers and wanted her own (she has no contact with her father - he gave up his parental rights). At this juncture, I went to her teacher and guidance counselor and explained what was going on. The counselor at her elementary school ran an 8 week separation/divorce group for kids that were struggling with this issue. It helped my daughter to see that there were others in her school that were going through the same thing. She made some good friends that way and they supported each other. You may want to see if your child's counselor does/can do a group like that.
I additionally had my daughter see a psychologist. God knows,thatt I talked to her about he issue anytime that she wanted to, but I found that I didn't always know how to respond to her. It gave me piece of mind that she was talking to a trained professional.
I hope this helps! I've been there. It is tough; and you're at the beginning. Keep your chin up though. Put your kids first and all will turn out well. Wishing you all the best!
M. L.