I, too, encourage you to write a factual, unemotional review @Loobyloo as other members have stated.
You might not realise that if you do not leave a review, that will have no consequence for the sitter as there will be no evidence of your sit on her profile and other owners will have no warning about her.
Should she NOT write you a review, it will appear on your profile with just the sitter’s name, photo and dates of sit. When you next advertise for a sitter, prospective sitters may wonder why there’s no review by her and cross-check to see the review you gave her. Of course, they will find no evidence of it.
As she is likely to give you a less than positive review, for your own sake and that of other members, please write her a review.