Boyfriend & friends

I don't like my boyfriend having girlfriends. Like it just upsets me because I've caught him flirting with girls & when I go to confront him about it he blows up and gets angry saying oh I can't have friends and blah blah blah. Do you ladies let your SO have girl friends?  I'm clingy and when I love I love hard. I hate to see him talk to other girls period. Am I wrong for worrying if he's talking to other girls behind my back ? Advice please?