Don't Confront Him
I don't think you're going to get much by confronting Bob. He seems to have a real problem. He can't take no for answer, and he doesn't have enough respect for you to stay away from others when you two have so recently "hooked up."
Stay Away From Bob
So, what do you want from Bob? Do you want to be friends with a guy who will force himself on your friends? Do you want to go out with this guy? I think you should do yourself a favor and stay away from this jerk. I would look hard at what you REALLY want from Bob. Do you feel like you need something from Bob that you can't get from others? Can you identify what I think might be a problem with wanting men like Bob? What I mean is that you should question your attraction to a guy of this caliber.
He sounds messed up. Stay away from jerks!