This guy sounds like he has you wrapped around his finger and he knows it and is using it 100% to his advantage which is
so wrong of him. I would say, if you can, to try and not rely on him so much. I know it must hurt to not be able to see him, but when you do finally see him, does it feel right? Knowing that he doesn't feel the same way about you and that he's just using you? If he is seeing other people (women, at that) and won't let you contact him, then this relationship is definitely not going anywhere, I'm sorry to say
You are so young and have so much to look forward to without being held back waiting on this 40 year old man to call you. I'd say that, however hard it may be, try and end it with him and find someone that can treat you the way you deserve to be treated.