I'm living a lie online
How are you living a lie online?
I'm actually a 19-year-old guy pretending to be a girl online.
If you are not hurting anyone, then there is nothing wrong with that. Just make sure you will end that female persona online.
I don't think I will end it, what's the point now that I'm getting everything what I want.
You're deceiving someone to get what you want, that is a dangerous game. Either come out honestly or end the online relationship. You wouldn't want to be betrayed by someone either online.