I agree with [b]crazed-driver[/b]. You’re worrying over nothing. Quit being the “bad cop” — in fact, quit being any kind of cop. You don’t need to be. Your boyfriend had drinks with an old friend or work colleague who happens to be single and female. He did everything in his power to let you know what he was doing, when he was leaving, etc. In the course of a long term relationship he’ll be placed in plenty of tempting situations and HIS behavior is what counts. It doesn’t sound like he betrayed you in any way.
If he continues to meet up with you without her on any kind of regular and frequent basis, then I think you’d have something to think about, but as you’ve written it, I think this was a harmless social encounter that you should be glad he wanted you to know about rather than hide.
I hope that helps — and that you’ll join me on AskApril.com on Facebook at this link: [url]http://www.facebook.com/group.php?gid=110265355684755&ref=mf[/url]. 🙂