I think I'm in love with my bestfriend, but I'm not sure. Any advice?

My bestfriend and I have grown really close in the last 7 years we've known one another. We talk on the phone almost every single night. That's all we can do seeing as we are not local. I fell for him a few years back but, things went wrong.. really wrong. He was actually chasing one of my other friends at the same time, and he kinda tossed me aside. It wasn't really that serious because, I got over the situation pretty quick. I basically weighed and measured him and chalked him down to a 'dog', and convinced myself I wouldn't want to be with someone like that anyways; but we remained close friends. It wasn't until recently that I started seeing a sweet, romantic, and endearing side of him that I didn't even know he could possibly have. Now I'm confused as to if I'm in love with him or just really love his friendship. Sometimes I think he sends signals of interest in me but I'm not for sure. He talks and confides in me about asking out other girls. Before it didn't bother me. Now I find myself getting strangely jealous and worried he may find 'the one'. Is this love I'm feeling for him or just fear we won't have that closeness anymore if he meets someone?