Angry Boyfriend

My boyfriend recently has gotten really angry at me for hanging out with other guys. He didn't used to have a problem with it, but now he gets angry if I'm with any guy at all. He even told me I couldn't go to my friend's birthday party if any guys were invited, or he would break up with me. I would just break up with him if I could, because you can't dictate who I speak to when you're dating me. But, he might have gotten me pregnant. So I don't know what to do.