What do you say to your kids. 

When we left in the beginning I told him that we needed to talk to the oldest 4 yrs old together. I told him we needed to sit down with her together and talk. So when he came over to do that he blurted out "Your mother is going to live here and I'm going to live at my own house but we both love you very much." while she was eating at the table and not sitting down together. I looked at him like I just saw a ghost. What? I told him why would you say it then and why not together like I said and what she needed. Of course since he said that I had to jump in and tell her the right way. She really didn't understand b/c she is so young. But now she knows that daddy has a house and she lives with me and her Meme now. Now she is asking to stay longer. I am going to tell him that we needed to have that talk again but I know that he will say it the same way b/c he knows that I will end up dialing with it so he doesn't have to hear it and break his heart. I will b/c I don't want her hurt or in the middle of it. The little one is two so he has no clue.

looks like Paula gave you some great advice. Explaining to children that are young is very hard.  They need to know that both parents love them but that they live with you and they get to spend longer visits on those weekends with him.  They might enjoy a nightly phone call from him to say goodnight.

this needs to be a shared conversation.  you two need to talk about how to explain this situation to your kids and be on the same page...and then both of you need to reinforce it with the kids.

i've tried to play up the 2 houses and 2 bedroom thing for my kids.  when they ask about why they don't see him as much, it's very hard.  i can't even say cuz he's working...because he doesn't!

how about other forms of communication.  we have a webcam.  they kids talk to him every night to say goodnight. i've suggested he send cheap postcards every other day, kids love mail.

i started a blog for my kids that we both share access to (it's private) and we both post photos and short blurbs about the kids.

hope this helps.