How to convince my family for love marriage

hi,
iam in love with a guy since one year.we were classmates in pg.he is very caring ,responsible.He is ready to talk to my parents but he wants me to tell my parents about this first, but i don't know how to talk with them because i know my parents especially my father he thinks that it is his mistake i would have made her marriage as soon as she completed her graduation, i would have more strict.he thinks that something is wrong with me only.but why don't my father thinks that if i marry my choice then i will be happy at end of the day that matters all because we live life only once.
our castes are also not so different almost all customs and traditions are same.from his side everything is ok he said his parents will accept.recently he got an offer letter from a very company he did this just for me to come and talk to my family.he always says that with everyone acceptance only we will get marry we will convince then and all that but i don't know how?
he says he cannot imagine life without me even i can't forget him.if i say something about this to my parents am sure they want me to get marry as soon as possible to their choice and they din't allow me to step out of the house they restrict me of using mobile internet any communicating devices they wont even try to think about my feelings why am loving him what so special in him let us talk to him once then decide they wont think in this way. but choice also have that every quality and he has a very good family which my parents choice person will have i think even mare then that because my guy understands me and love me more than anybody.
ofcourse my parents only think about what society and relatives will say but if am unhappy they wont come and take my pain ultimatimately i should bare this pain my whole life they just come for marriage and go and will be busy in their owm lifes.
In this situation what should i do plzzzz suggest me...