Feeling Depressed. She says to leave me.

I think I am mentally depressed.. I know what is going to happen next..but still I'm not able to defend myself... actually the problem starts with that I love a girl...just limitless.. she too loves me but she gets hyper over little thinks and makes out a big issues over it...we want to marry each other...but due to her family..we can't get married... although I know that our marriage is completely impossible but still I can't detach myself from her...she speak lots of lie to me but still I'm not able to leave her...my anger over her lies only for few minutes... whenever she says to leave me...I feel like I'm going to die soon...I'm not able to focus neither able to eat or sleep properly...I want to completely get rid of this problem...please help me out...