How do you know when you really truly LOVE someone? It's all I've dreamed about since I was little, and I've finally met someone that loves me, but how do I know I love him? All I do is listen to love songs, write/read love poems, read love stories, and think about love, & I thought I understood, but now I'm not so sure. Here is my story, I need advice;

I met a guy & we instantly clicked, but he had a girlfriend who lived 500 miles away, & then for about 5 months he cheated on her with me. Don't worry this isn't the guy I need advice on. I thought I loved him, but I realized later he was just using me. He lied to his girlfriend about the affair & that pissed me off, because it wasn't right to her, so I told her. & they're still together, but we don't talk anymore. The point of that story is, the guy, let's call him J, had a best friend 300 miles away, let's call the friend Z, well me & Z started talking & when we started talking I was dating someone & he was absolutely in love with this horrible girl. My boyfriend & I broke up & I started to really like Z, & eventually I fell in love with him. He didn't talk to me much & he was still in love with this other girl (the horrible one). One day something happened & I log into myspace to read about a million bulletins about how much he loves her & all this stuff. It broke my heart, it was then that I realized how it had always been me calling him & how he never talked to me much & I was nothing to him. I cut myself a lot & stopped talking to him & decided to "hate" him. A few months later (right before me & J stopped talking) J was visiting Z & they started talking about me. Then they called me & Z started apologizing profusely & long story short he never meant to hurt me & we became friends again. Later that night he asked me out. I didn't really think about it, even though it was long-distance & he had hurt me. We rushed into our relationship, but we really clicked (better than me & J) & he was so sweet & perfect & like an exact male version of me. A few times I did stop & question everything & try & think about if I really did love him. About a month into our relationship he drove over to visit me for a week. I'm having a really great time, but I keep thinking about J & I keep thinking about if I really did love Z. Z obviously loves me so much. I really don't understand why, I mean I'm not attractive(he's gorgeous), I'm a horrible person, I cheated on him once(he knows & he forgave me[???]), & eh knows about what happened between me & his best friend(J), but the point is he loves me so much. I really care about him & we have so much in common, but how do I know if I love him? I've told him I'm confused & need to think about how I feel. & he's offering me a choice: I can be with him, & love him, even though he lives 300 miles away or we can put our relationship on hold until he moves down here in 5 or 6 months & still be really good friends.

So basically what I'm asking is how do I know if I love him???? What should I do???