Does love REALLY exist?

Hello readers.
I've got a huge problem. Yeah, this problem is what you think it is. This problem which tortures our lives, a problem which is there once or twice or lots of times on our lives. Yeah, I'm talking about love.

Do I love? Do I have to love? Or do I have to be loved? But, does love really exist? Well, I can answer the third one for sure: Love exist. But not the way we think it is.
As our biology teacher said once, love exists. You know, I love this man (not in the couple way), he's amazing, he know about everything, has studied everything and so on. So I believe love exists if he says so.
The big shock was after saying this big truth, he said love is just chemicals. When e're in love, we release some kind of chemicals and the other person also does, and we receive both, and then is when mutual love exists. Then, love lasts just for 6 years. When this time has passed, you really stop loving that special someone, that, over those years, has became the normal someone, the ordinary someone, when things aren't just the same. Time to change partners.
And at my age (17), I'd have been in real love like 3 times. I wonder if what I felt was really just a chemical, or my soul was really trying to share love to another soul.

Well, after this big big introduction, I have to do a confession or maybe a question: Do I love my teacher?
Doesn't it look like a question from Yahoo Answers? A simple English question, with just five words, is really panicking me.
As I said in older posts, I was in love with my Philosophy teacher. But, he already is married, has got a son and a daughter, and he really looks like he's so happy, and I couldn't make him even more. I just knew. I even tried. Just looking into his black eyes, was much for me. He, as an adult, thought I was just interested on his subject, but the truth is, I was so much in love with him. And I still am.

But in Wednesday 13th of this month, I met someone: my Physics teacher, called Marc (my Philosophy teacher was called Manel, so I'm sure my unconscious part really likes men with M starting names), who first, I really did not care about him. He was like two classes talking about ancient Greeks or something, I didn't really listened, I just looked at him. Not few days after the first class, I noticed I was waiting for his classes.
And when I was with him, everything was funnier, and I felt like I was starting to release some chemicals. Yeah I was in love now and then.
Things that must have influenced my love for him: for example, comparing our hands. The second or third day with him, I don't know how, he said he got big hands. You know, I also have got big but feminine hands, just for being a woman, so I compared with him. That's part of the story.
Also, I'm sure him looking my book too much close to me, and then looking to my eyes just like that, you know, we were just 10 cm away or so. Too much for my heart.

To sum up, Love exists, I love him and I find him interesting, and now I'm trying to tell it to my friend. Let's see what happens!