look urs is a very critical situation, as both of u are adults and can marry as per ur wish and will but the parents are not convinced, plz convince them, legally there is no way out. as far as safety of the boy is concerned, u cannot even make a police complaint against ur parents which will hamper ur relations with ur parents. thru love try to manage the situation and if not solved, make a police complaint of threatning by ur parents abt ur bf and send a scanned/xerox copy to ur parents, ur parents will be very much afraid of such complaint seeing and will never even threat or make any remarks/injury to ur bf.
this is the only way out
best of luck
kisen agarwal
kolkata advocate