IM SO CONFUSED!?!?! I think I'm falling in love with my best friend...?

Hi, I'm 18 years old, and I kinda feel a little too old to ber asking this, but whatevs. So about 4-5 months ago I met this girl. At first, I didnt like her that much. We starting talking and hanging out a little more, and we actually started getting along very well. Actually we grew closer and closer every day. The more I hung out with her, the more I wanted to be around her. As our friendship grew we both realized that we love each other: but, you know, that friendship love. We're pretty much best friends at this point. Then things took a different turn. Her boyfriend cheated on her, and she took it really hard. As u can probably imagine, they're not together anymore. After that, everytime we talked, she seemed less energetic, and just plain sad, even though she would cover it up in a sea of weird corny jokes. All I wanted to do was make her feel better, all I wanted to do was make her laugh. She would always tell me that I was the best, and when we hugged each other it was like, a more meaningful sign of affection, but again, more like a friendship affection. Its hard to explain. I then found myself thinking about her all the time. I started daydreaming about the two of us in each others arms and walking down the street holding hands. I would get giddy when I was around her, and when she laughed and smiled, I would feel warm and comforted. I would think to myself "I'm falling in love with her." I sort of wanted to tell her how I feel, but I wanted to be smart and not screw up our relationship because we're both happy. Everyday it got harder and harder to do this but I still kept my cool. However, recently, very recently, things are kind of changing again. She seems back to herself again. She's having more fun, she's crazier, and she tells more inappropriate jokes. And I have the best time when I'm around her. It makes me so happy to see her happy. Now I think I'm kind of losing the strong feelings I had for her. I'm starting to wonder if it's what I really want. But theres still a part of me that really wants me to be with her; partly because I want her to be happier than she's ever been in her life. I'm not saying I'm mr. perfect, but I would sure love to be the perfect guy for her. I dont know what to do/think of this. When I think about her like this and I'm not with her, it hurts me emotionally. I often find myself lying awake at night, thinking about her. As I'm sure its pretty obvious, I don't have a lot of experience with girls, so this is still a little new to me. I'm not sure how she really feels about me.