Love Marriage

I am a sikh girl with an age of 24yrs and my boyfriend is a Catholic with an age of 34yrs. We are in a relationship since 4yrs and we both are independent we both are working. My parents are not ready due to age and caste. I have tried convincing my parents twice but they are not ready to accept him. Twice they have a lodged a complaint against him. They go to the police stn and ask the police to threaten my guy, as complain cant be filed till the time I don't be available over there. My dad's brother in law's friend has some reference in police so with his help they go and ask the police to threaten my guy. They are not at all ready to speak to my guy. They won't allow me to get married to him. Now we are planning to get married but we have a fear that if again I speak to my parents they might again file a complaint against him and they will lock me in the house and take my cell ph also and again I will lose contact with him. Now before I tell at home, I want to secure our boths life, I can't complain against my parents also. But I want our boths life to be secured before I speak at home. Please suggest that what is the strongest way in which we can secure our lives and then we can take a step of marrying each other.