bad situation..

I saw my ex outside a store today and I almost threw up because it wasn’t a good relationship, I had just turned 15 and he was 19. I snuck him over, would let him hang out with me in my house when my parents weren’t there.

Now he’s 21 and i’m 17 and I’ve seen him twice in two years and every time I see him I just get stressed out... Who do I talk to about this.