How to convince my girl friend and her parents?

Tricky. Firstly, you're never going to convince her parents of anything, they are too entrenched. If your GF is going to allow herself to be blackmailed by her parents, then I am afraid there's nothing you can do about it. They won't commit suicide, but she clearly wishes to please them. We both know she'll end up being miserable and ruining her life. Unfortunately, you have to persuade her to marry you, then there is nothing else her parents can do. Short of kidnapping her and taking her to Vegas and marrying her, there's not a lot you can do. Can you go to her, meet her somewhere, and when her parents don't know? Keep talking to her anyway, at least until she says you mustn't (she hasn't said you mustn't call, only that you must use a method that her parents can't track), and then you have to stop, out of respect for her. You might try re-balancing the scales by threatening suicide yourself. Good luck, I really hope it works out for you, but I have a nasty feeling it isn't going to. Sometimes the obstacles to love are just too great.