How to tell kids their daddy doesn’t want to see them

I have 4 year old twin boys and a 3 year old daughter. For the past year my husband and I have been fighting nonstop and last month we decided to get a divorce. My husband moved out the day we decided to get a divorce and the kids haven’t seen him since that day. I have been calling and texting him and he doesn’t reply. I finally got a text last night that he will sign all his rights over and that he is moving out of the country. I have no idea how to tell my kids. What do i do?