I am repulsed with my boyfriend Please Read and Advise!?

Started talking to my current boyfriend in november. When we first started talking, he was talking to a few other girls, which was fine because we were not in a relationship. However, now 7 months later I find out that both of the girls were 9 years younger than him, he is 30 and I am completely repulsed. I am supposed to go out with him later on today and can't fathom even sitting next to him. I feel as if he is a pedophile. Do I have any justification in the way I feel? I can see later on in life it not being so much of a problem, but at 30 and 21? Something seems really off.