I need help

I met this girl on here after she posted a nude on medical advise. I dmed her to tell her my opinion. We got to know each other and we hit it off. We started talking for a few days and after the third day we starting sending stuff to each other. Well I found out she was only 17 when she said she was 18. I just turned 22 I didn’t think there was anything wrong with it until I found out she was 17. I cut off all communication with her. Did I do anything wrong? What do I do?