Ok. So you've made a decision. Good. Better than waffling about with it. Just don't let her make it a steady diet of taking them for the weekends.
Remember, this is her choice, not yours. They need to feel the repercussions of her decisions. Like robx said above - if down the road you end up with a custody plan, she'll be away from the kids then too. So if she doesn't like it now, she better change course or she'll be dieting more on what she doesn't like.
You did good standing your ground and telling her you didn't want her home under the 'reasons' she gave. (If you can even call it that)
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!