A. Shrug. Not every book is for everyone.
B. Cry. Have a drink or two. But realize at the end of the day that not every book is for everyone.
C. Rant about it in a locked, safe space where no one will see it except people you trust. Let them pet you and commiserate. But realize at the end of the day that not every book is for everyone.
D. Have a enraged meltdown on Goodreads and attack the reviewer and everyone who subsequently tells you to calm the heck down, calling them stupid, immoral bullies who are exactly what is wrong with the world.
If you picked D, then, congratulations, you're this guy.
Honest one-star reviews gonna happen. Hell, with a book coming out in September, I'm bracing myself for them right now. I'm even bracing myself for dishonest ones from people who haven't read me, simply because of my politics, honestly, because those gonna happen too. But if there's anything that watching this business for all these years has taught me, it's that you can't control what other people do. All you can control is how you react to it.
I realize that reacting calmly or not at all to something like an unfair one-star review is hard. Trust me, I have more than once typed out an entire paragraphs-long screed lambasting someone for something--and then deleted it unposted after taking a deep breath. I do not have the time or the spoons to get into internet slap-fights. For some people (Larry Correia, I'm looking at you), it's a contact sport they enjoy and are good at. For me, it just ends up knotting me up inside and making my hands shake, if it goes on too long. I mean, I enjoy a skilled takedown of an idiot (and not everyone--or even most people!--who have the temerity to leave a one-star review on your deathless prose is an idiot, FFS) as much as the next person, but damned if I have the energy to do it wholesale. I'd never get anything else done.
Come across as classy and professional in the face of adversity, and you'll end up on top. Come across as a raging dick, and, well. You'll be the poor trainwreck in the link, embarrassing yourself without even realizing you're doing it.