Tell them together. Tell them at a time when you would normally be together, like after dinner. Start with what they already know....mom and dad have not been getting along. Tell them we have worked on it, but can't reconcile our differences, so we have decided to get divorced. We want you to konw that we love you and this is not your fault. We will still both be spending time with you, but we don't know yet what the living arrangements will be. There is still a lot to figure out and it will be difficult, but we just have to do our best. Do you have nay questions?
Something like that anyway. I am really dreading going home tonight.