Keep her. Of course I would be disappointed too in this situation, but would always put the bunny's welfare and happiness first! If this woman has so little regard to this bunny's welfare and is so unco-operative now, what is she going to be like if things aren't going according to plan?
And she has also kept important information from you... so what else is she hiding?
No way! Keep the bunny with you where she is safe and happy.
Vera