Hi NW: I was surprised to read that she has the right to take your child across the state line - that just was not expected at all...I wonder if it's worth looking into that a bit further - though I do see the wisdom in taking care of your interests before she has set up residency.
Hope it goes okay tonight - and that she doesn't try to bait you into R/M talk or any type of tension. Good idea to see her as just a guest in the house.
Be strong, my friend - and let us know how we can be there for you.