Your greatest power right now is disappearing. No texts, no ‘accidental’ run-ins. Let him believe you’ve completely forgotten about him. Once you’re totally out of sight, he might finally start thinking, ‘Oh, maybe she wasn’t that crazy after all.
Listen, if you ever run into him again months from now, just give him a slight smile and keep walking. There’s no need to bring up anything from the past. Your silence will confuse him, and when things have gotten this messy, confusion is always better than desperation.
April was also right: It’s not a rule that everyone you like has to like you back. Move on and find someone actually interested in you.