OMG! She did it! She asked to stay over at your place on the couch! Why am I not surprised by this? She still looks to you to rescue her or fix her problems for her when she doesn't have an op waiting in the wings. The only person that you need to be concerned about at this time is your little girl.
If you opt to help her out, be sure to set some boundaries and stick to them. I would hate to see you burned once again for being a kind and generous person. BTW, if you do allow her to stay, don't make it easy for her...she will need to pitch in around your place and share in whatever expenses that she incurs while she is there.
BTW, I did step up to the plate when my xh moved out and he had no place to go for one night and I allowed him to stay. I never regretted it because it did show him that I did not lower myself to his current standards. Did he appreciate it after the fact? Nope. But I slept better knowing that I "turned the other cheek" and helped someone out.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.