I feel guilty for keeping it to myself on the chance that maybe he's done it to somebody else after me.
What do you think he's been doing to somebody else after you?
Well he was abusive, and I think he's currently sexting other girls and maybe even dating them.
Sometimes you have to be proactive and prevent possible harm. It's good that you want to prevent something bad that happened to you from happening to others.
I think I'm going to report him to the police.
I think it's a good idea that you do that. By telling the police you could prevent it from happening to anyone else.