Your father doesn't seem like the type to listen to anything you have to say, and in any case, attempting to get revenge through CTB is pointless given that you're not going to be around to enjoy it.
If you're insistent on trying to make him suffer, though, I think a more effective approach would be to do something to shame him and lower his social standing in the religious community he belongs to, making him look like a failure in some way in the eyes of those around him. Bonus points if you can get him fired from his job or ostracized altogether.
A highly unethical example that comes to mind would be to, instead of writing a letter telling him you're gay, write other people a letter claiming that you're gay because he molested you or whatever and that this is your motive for wanting to die. That's a crock of homophobic nonsense, naturally, but that makes it the kind of thing that socially conservative communities eat up. There are a number of reasons you shouldn't do this, of course, but it might help give you some ideas about what you would want to do.