Should i be with this guy?

I have been dating this guy for 7 months now (we dated b4 this too) and we got engaged on july 13th.. Well he is turning 18 on friday and things are really hard.. His dad is telling him that he can find better people then me to be dating and he tells him all the time that i am the only girl he loves and wants for the rest of his life. Now i found out from his friend jess that he has been lieing to people about being engaged. I take this stuff sersously. His dad does not like me much and is trying to break us up but we still see eachother.. And the only time we ever really get to hang out is when he wants to have .. Is he useing me?? I need help??!!!