Plz help...i like both the boys....whom to choose?

i'm 17yrs...a boy who is 21yrs proposed me before 2months...i ignored him for many days but he impressed me a lot and i accepted him...he asked me for a date but i have no feelings towards him..i just like him...i never felt to kiss him though he is smart....i met another boy in yahoo answers and i chat with him everyday....he proposed me and i said that i was fixed with that boy..he said to be as his girlfriend and i accepted..we used to chat everyday....he asked to see my picture and asked my phone number and i haven't shown him yet...he has some personal problems and depressed...he said me that he's going to die and i was very scared....i cried a lot for him...without food and rest i spent my whole day crying.....i got no replies from him and i thought he was dead....in the evening he replied that he was alive...i felt relaxed and happy..i chatted with him for many hours and i felt very sad while signing off.....i cant imagine the first boy but i started to develop feelings for online boy...but i like both of them.....i'm very confused and i really cant concentrate in my studies.....first boy meets me everyday but i just give him smile....i'm feeling that i cant live without chatting with online friend.....i really like both of them and i like online boy very much...but our families and cultures are different......what should i do now??plz help... And plz dont give rude answers... Thank you :)