So slow down on the assumptions about his sexuality and the world ending. For a lot of people porn and only fans is just a harmless fantasy.

On the other hand he may be pansexual and he hasn't told you. That doesn't mean that you need to break up. Unless you can't deal with it.

There are really two things you need to work through. One he's spending money on Only fans that clearly he doesn't have. That's a big issue.

And two whether you want to be with him and whether he wants to be with you.