how do i really feel?

Hey ladies so i really  need some advice. So i met this guy over  a year ago, we will call him James. James and i started out on the wrong foot, he even called  me immature at one point. We were able to overcome all of those arguments and decided to give it a try and  be friends. We became really good friends, people around us would say that we were dating. That was not true by the way, we never dated.  He kissed me once and he told me that he found me attractive. I did too but he was very clear from the beginning and he told me that he didn't want to be serious at all. So we started a friends with bennefits. So we started to talk on the phone more and more. He told me that the reason why he didn't want something serious was because he was in love with a girl. He knows very well that he can't ever have this girl.
Next week he is toing to hang out with friends, this girl is among them. Why is it that i feel weird about this hang out?  I don't the idea of him hanging out with other girls. He always ends up making out with them. Everytime he tells me that he made out with someone i feel weird. Why is that?  I know for sure that i don't have feelings for him.   I kind of want this hang out not to happen
He lost his virginity to this girl, and i lost mine to him