Since your coworkers already have access to the book, I doubt there is anything you can make the author do to reduce your embarrassment and upset. I recommend you take the position that the character in the book is "What if Elisease but times 1000 and with added weird and evil?" You can say out loud that you wish the way-more-evil, way-more-clumsy, way-more-cringe than you character was not so obviously based on you. You can make jokes about what Fictional Name would do in a particular situation. You can even make a little fun of the author for having so little imagination as to base the name and half of the villain's personality on you.
That's the public face. Not quite laughing it off, but laughing when it's brought up and pointing out the book is fiction. Use the cake incident as an example of the x1000: you dropped one food item; Fictional Character drops many food items. That sort of thing. If there's anything Fictional Character did that you didn't, use that as an example of "added weird and evil." Ideally at least some people will consider any gossip in the book they didn't already know as fiction, too.
In private, I would go once to the author. I would tell them I was embarrassed and upset by the mere existence of this character, and that the author's laziness in using so many of my characteristics had extended that embarrassment to the workplace. I would (probably angrily) tell them there was nothing they could do to make it right, that I was not looking for an apology, and that I didn't want to ever discuss this matter with them again.
Then I would go to my boss and ask for suggestions about dealing with my feelings of embarrassment at having this character modelled on me. I wouldn't actually expect my boss to have anything useful to say, but this would enable me to move on to HR without "bypassing" my boss. It's possible the boss had no idea about the book and you might have to provide the same precis you have provided here (maybe leave out the NSFW incident, you don't want to confirm that part as real.)
After that you can go to HR. They probably won't have anything super useful to offer either, but you document the meeting and the date. Firing people for things done outside of work is rare. However, if you think the author wrote the book and distributed copies at work to harass you, HR may get involved. That won't be their first guess and you may not be able to convince them that this is harassment.
After your work meetings, you pay a local lawyer to write a letter to the publisher asking that the book not be printed any longer at all. They may ignore you, or offer some sort of changes in subsequent printing (the extraordinarily lazy name for example). They may drop the author; ideally you wouldn't care but probably you would be happy if they did.
Finally, if you feel your coworkers cannot settle down or switch to making fun of the author instead of you, you may need to leave the job. Find a new one first, of course: I can't see any court, even small claims, awarding you lost income as a result of the egregious behaviour of your coworker. Unless, as mentioned earlier, you feel this is targeted harassment; that may open some doors to compensation, but of course will not stop gossip and snickering.