Lust or Love?

So I've got a problem.  It feels a lot like fear, paralyzing, debilitating fear. My hands will literally  start to shake if a certain guy comes into the same vicinity as I am in.My armpits get that prickly feeling and I really just want to run as fast as I can in the opposite direction. Then there's this other completely contradicting feeling, an unfamiliar pull . I've been saying no for 18 years now and then here comes this guy and makes me wonder for the first time what I'm waiting for. My problem is I cant figure out if  this unfamiliar pull is lust or love. He's the first guy I've ever emotionally opened up to even in the slightest amount. I don't want to say here's more then have him take it and go.