As I read it tbart she's asking you for them THIS weekend only. Is that correct? If so, then I would do it. It does show you empathize with her position. I imagine it's hard for her to be away from the kids - but if this is hard for her, she's in for a rude awakening if she decided to separate.
This is why you need an MC. Although the communication channel is open there's a lot of confusion. I think there is also expectations from both sides that are not really being expressed. ie: She's asking you what you expect after only one week. She has her expectations and you have yours. The confusion is mixed in there. It's very difficult to untangle the issues and miscommunication because they are so inter-twined; it will take a third party to help separate them out so they can be seen and dealt with one by one.
I agree with your boundary. If she wants, she can stay somewhere else and come in and out of the house as she wishes. But you stay put!
Don't flinch when she throws the victim card out there - as in "I'll sacrifice myself for the needs of the kids".. it's just drama.
Did you ask her what she expected after only one week?
MySitch Me-47 STBXW-41 D-5 S-8 ILYBNILWY-01/08 Want a D- 01/09 Physical Sep-01/10 D filed-06/10 Got 50% custody=09/11 Ride that wave!