I don't know how to go about talking to my boyfriend about how I feel to him talking to other girls, I'm scared to lose him to someone else, and I don't think that will really happen but I need him to know how I feel, how do I talk to him?

If you want to communicate with him, talking is the only option. Your boyfriend is no mind reader. And if it doesn't end well, then... He wasn't man enough for you. He should be able to listen and be understanding at the same time. So don't waste your time on a guy who'll dump you for little things like that, it ain't worth it.