I can see trusting someone enough to share info about past sexual dalliances, but I would not share names too. That was unfair to you and his friend IMO anyway......

You are not being a bitch about this at all.

Your bubble has been burst and it will take time and effort from you and your boyfriend to work through your angst about this news. Just keep the lines of communication open and hopefully you can put this behind the two of you.

Does the friend know he told you? If he does maybe he would agree to talk to you and allay your fears and calm your uneasiness about the two of them.