Love, lust or lonliness?

Here's my issue this week (well, it's not something that came about this week, or will go away at the end of it), perfect girls. I've never believed that one girl could have all the qualities a guy looks for, until recently.
Yes, I am talking about one girl in particular, and I know her life probably isn't as perfect as it seems, but that's not the issue I'm addressing - I'm saying this girl is absolutely perfect for the guy I like. And he knows it, clearly, as they dated for 6months. So, someone please tell me how to cope being compared to the guys ideal girl!?
She's gorgeous - a complete knock-out - she's clever, she's rich, she's funny, she's well-behaved and most of all, she's just oh so nice. And when compared to her, the things I like about myself suddenly seem like things I should be trying to change. I may be a pretty, sexy girl, but I'm no way near her level in the brains department, I don't live in a mansion with a perfect family, I'm badly-behaved, recluse, and if we're honest, I'm not always that "nice".
Before it's been the spontaneous, sexy, dangerous side of me that's attracted men, but now I'm being judged for the Bellini/Marlboro light in my hand. And who can blame him - when sat in between me and "Miss Perfect" why would he choose to listen to my drunken flirty small talk when he could be having an intellectual conversation with an equally beautiful girl.
He says he doesn't want to get back together with her as she's too busy with her work and family for a relationship - but it's quite clear he's still in love with her, and how does the new far-from-perfect girl even think about competing with this "perfect" girl, who he has a deep meaningful connection with.
It's just got me thinking, am i destined to always be the "go-between-girl"? The one who is good for a bit of fun, to rebound off an ex, before finding the next "Miss Perfect" to fall in love with. And if I don't want to be seen as this girl anymore, does that mean I have to completely change who I am? Stop the partying, the drinking, the smoking, the lads and the general fun? Well, if it does then I guess I'm the "go-between-girl", because I'm not giving up my fun for a guy, who's not even that exciting (and I've had cuter, to be honest!)