How do you handle negative reviews?

That is a tough situation Anita. I think you handled it correctly. Ideally you want to make sure you check in with the person and offer anything you can do to mend things. I've been in similar situations and in the end realized I was not a good fit with the client. It would have been a true struggle to keep them and cost me more time and energy than it was worth. These are situations you are thankful for in the long term. Even if you have to go through all the negative energy to do it you probably do not want them as a client.

We creatives are paranoid enough as it is, without people slamming us behind our backs. I agree with Corbet that a client who would do that is not worth keeping. S/he is not being a good advertisement for your services. And s/he is too cowardly to talk to you about her dissatisfaction with what you did. Nine times out of ten, the client didn't give you the right input at the beginning. Maybe that's why s/he didn't want to talk to you.

You can't please everyone. There are a lot of passive agressive folks here in the PNW, and sadly, you've met one of them.