Boyfriend out of me league?

So I've been dating this guy for about 3-4 months now, on and off, and only recently have we started going steady. He's funny, charismatic, extremely attractive and overall a really nice guy. But I feel like I'm always on edge, simply because of his social life. He has a ridiculous amount of friends, to the point where we can't walk around the city at any time without him bumping into SOMEBODY he knows. He's had more girlfriends that you can shake a stick at (ridiculously pretty ones, too). He's had more one night stands than I care to mention. And he's always around girls- like, always. He used to model for Jack Wills, so many of his female friends are models themselves, which doesn't help my self esteem. I'm not normally a jealous type in the SLIGHTEST. If anything, all my previous relationships were the other way around. But it just makes me feel a little uncomfortable and inferior when I'm around him, because I only have a very small group of close friends and I'm really sort of shy. I want to say I trust him, but really, I haven't dated him long enough to know for sure. He's always got girls hanging on his arms wherever he goes, whether I'm there or not, and it just makes me feel a little insecure. Not to mention his ex-girlfriend of 3 years has recently got in touch and wants to meet up with him for drinks. He asked if it was okay, and I said it was, but really I'm just nervous as hell about it. We went on this strange little break of not seeing each other for a month, back in December, and in that time he admitted to having sex with 2 girls. I know we weren't together or anything like that, but it just makes me worry about what he's capable of when he's got the time. How do I get over these feelings; or talk to him about it in a way that doesn't make me come across as clingy and insecure? And I KNOW that that's exactly how I'm coming off, but just think of this as a little rant where I'm piling all my little nagging problems into these few paragraphs. I'm really not so dreadful, but I thought I should admit to every little insecurity for the sake of getting the response I need. I never admit to any of this around him, so it's just been kind of building up over the last few weeks. I'm sure you've all felt similar at some point in your lives.

Put the internet to work for you. via Personal Recipe 2629979