I'm gonna go against the grain and say I'm on the side that there's a good chance the kid is not even yours [OP].
DNA should be your main priority before parting with one more baht. If she refuses or leads you on some wild goose chase, that could be telling you something.
Outside of this, its one thing to be generous & to get anything going with your child on your terms [if it ends up being yours], but rule with an iron fist. Your way or you walk. By now she should know what value there is with you in her life or not. They need have some fear instilled in them, that there is more to lose by not having you around. Then you have the issue of dealing with a drugged out **** which is another major obstacle.
Good luck, it seems you're against the odds, but only you will know in the end to what lengths you will go to for an amicable agreement and relationship.