Is it okay to cry over a guy?

I'm always told to never cry over a guy but I can't help it! It's like sometimes he's all about me then other times he wants nothing to do with me and it's really hurting because I've tried to damn hard and I shouldn't have to try , why does he keep playing with my emotions?? I haven't fully ended things with him yet, I want to do it in person and the thought of not seeing or speaking to him again is really killing me, I just hope I'm strong enough to say what I need to say.