(Yeah I like using “open” too sometimes, I used it a lot when I was younger.)
If you don’t feel like it’s safe or gonna end well if you come out to them, I’d say please don’t, at least not yet. It’s best to wait until you’re an adult and have some form of financial stability, or a backup plan like a friend who would allow you to live with them. If it’s safe too, you could try and gradually open their minds, like talk about “a gay friend I have” and break down their stereotypes…but that can take a long time and doesn’t always work.
I’m sorry. Please hang on tight <3 and perhaps unload the pressure by coming out to a friend, in order to build a support network around you. And you can always vent here if you like too, my messages are open.