Don’t feel bad for blocking them. Like Lady said, there are people out there that has nothing better to do than harass people online. From what I’ve read from your post, you’re an amazing person that helped a lot of people during the pandemic and chances are the people you’ve helped will keep that bully safe.
So focus on the positive. Focus on your well-being. I know it’s hard. I get crushed too when people say bad things about stuff I create. It will hurt today, even tomorrow, but on the next day, open your computer and start writing a second book. You’re creating, you’re making money, that bully will always be a sad person on the internet, that doesn’t want to get a life.
Keep your chin up.