How Do I(18TF) go about contacting a lawyer due to my crazy ex (19TM)?

Me and my ex broke up about 5 months ago in November shortly after my birthday.

The situation wasn't handled well and we had a very messy and hurtful break up that was stretched out over 2 months. This would climax in me just going off on him and my parents kicking him out.

Since then, I've gone from being the crazy ex to him being the crazy ex. Initially, I tried to stay on good terms with him, though my methods weren't the greatest, if not a bit obsessive and stalker-ish.

About 3 weeks after, I had stopped stalking his accounts and started going to the local college to use the new free time I had to do something productive and healthy.

Unfortunately for me, he's the student government secretary. So on the second of me consulting College services about re-applying, we ran into each other. It was a very shakey situation and did not leave a good taste in either of our mouths.

Since then, he's blown the situation way out of proportion. He's villianized me to our because of issues in our ex-relationship (things I've been working really hard on improving on). This then culminated in me finding out about him spreading our interpersonal issues to the entire college. This made feel really ashamed, and I ended up cutting ties to the last of our mutual friends since they were on his side in the situation.

Today, just moments ago, I found out that I have now been banned from showing up at the college. All because he assumes that I'm at the college because of him.

How do I contact a lawyer about lawsuit for defamation? I feel like my ex is going out of his way to ruin my life over selfish assumptions.

Location: Florida