I'm feeling the emptiness already

Well my kids are leaving in 4 days, and I am just so emotional already, and they haven't left. I've spent the past few nights just laying awake holding them as they sleep. My heart feels like it's being ripped out of me again, and I can't stop it, or do anything about it. Finally I'm in routine with them, and we're happy, and it's time for them to go. I would never wish this pain on anyone in the world. I just keep trying to pray, and know that the Lord will get me through this, but then whatever the evil is in me decides to make me think why would God allow all of this to happen in the first place. Why did I have two Beautiful children that love me so much that have to be so darn far from me. I hate it, and I just want to enjoy these next few days, but I keep finding myself going into my room, and just laying there in a foggy cloud of doubt.