Mental help please ?!? ?

I am 19 and i hav a girlfriend and we went to the same school and we know each other since 6years and i didnt get to know her till the past 2years and i fell for her :)...and i asked my family and later requested her to let her family know about it and they are fine with me and we are gettin married in 2016 :) and the thing is my dads sick hes fightin cancer and i need to take care of him even though he didnt like me over the past and his days are endin up and im utterly depressed and i even told her and her family about my dads condition and when ever i talk to her she just says shes enjoyin partyin ...at the exhibition ...at restaurant...enjoyin with friends...partyin with family and things....i dont object things but i really cant take those in mind and i never left a moment leavin her behind i will cancel my friends and things and just to speak to her and i dont know what makes her forget me and also i dont share things to friends and only cousin who shared died suicide last year and i was depressed and tried suicide but dad pulled me out and life feels like bullshit rit now ...feels like dyin ...so please help me ...and yea my family doesnt take care of me with luv ...my mom loves my elder brother ...and i had my father but he wont be gettin past this year...