My condo rules do talk about noise at night but in the master deed it does give the condo the right to remove any pet for any reason. Just pointing that out could be enough to make her take it seriously.

I wouldn't worry about looking unreasonable. It isn't unreasonable to want quiet enjoyment. Some people are just the type who try their best to skirt he rules and you have to be harsh with them.

She is the one who needs to move.

Also, if others have complained you will be adding to their claim. You have been reasonable in talking to your neighbor.