I need some cheering up :[?

So, I know I'm going to sound like one of those obsessive girls, but I'm really not. I've kinda been taking a liking to my best guy friend, who lately has been taking a liking to me, so we've been having this weird jokingly flirtatiousness going on for quite some time. Today, he changed his relationship status... and he's seeing this awful girl who is 2 years older, and actually is completely obsessed with him, but in a really stalker-ish way. But he doesn't seem to mind. Either way, I have a feeling they may be going out for a while, and that he's going to report all of his endeavors with her to me because we're really close friends, and I don't think I'll be able to handle it. So right now my heart is aching and I just really need some cheering up and reurance. Thanks.