Every now and then an author reacts online to a bad review. And I wish I could give him or her the best piece of advice I ever received about reviews. It was from science fiction author James Gunn.
It was this.
"Read the last line first".
Simple and effective.
The last line tells you whether the reviewer liked the book or not. Then you know. Whether you actually read the review after that is up to you. I know several authors who don't read their reviews at all. Not even the glowing ones.
If you do choose to read a bad review, then read it, shrug and move on. If the reviewer goes in for an ad hominem attack, you can smile while you shrug. That's not a reviewer to take seriously.
Don't respond. You'll be seen as "hitting down". This always sounds bizarre to authors, many of whom reside well below the poverty line, but there it is. There's a widespread perception that we all have castles in Scotland.
Bad reviews are not fatal, to you or your book.
Just remember to read the last line first.