I can see why you're struggling.
It would be easy to say "Just be yourself, if they can't accept you for that then you're better off without" but if you have nowhere to go, you can't do that.
The only thing I can suggest is that you apply for the universities you want to apply for and then, when you're there, you can be open with them about being gay, about not wanting to be in an arranged marriage. You will have somewhere to live and they won't be funding you so you will have your independence.
Do you think that might be something you could do?