90% sure I don't still like him, but I still get those feelings... WHY?

So a SEVERAL months ago I started liking the one guy I promised myself I wouldn't, and I swear I've let him go a long time ago. But it's like every time he texts me or talks to me in any way I get the jitters, I start sweating, and my teeth chatter. Like what the hell I've never done this with any other guy and I DON'T EVEN LIKE HIM. WFT any ideas? Not really an important question but I just wanna know why