Two days ago, I swallowed a small piece of plastic which was broken from a fork I was using. Would it be harmful to my body? Would it get digested?

It could be. Harmful, as if it was sharp, it could have damaged your intestinal tract ranging from your esophagus all the way to your colon. But if it was a very small piece, more than likely it became encapsulated by your stool and at this point, you've likely already pooped it out. You can't digest plastic. At this point, you need to monitor for abdominal pain. If you develop pain reach out to your doc.