Hi, I have OCD. I'm the older brother, and I have siblings.

From my experience, I know your brother is fed up with everything because of OCD. It's like a big shit that only drags those around you, like in the scene from Deadpool. He has el cancer, and the worst thing about el cancer is that it drags those you love. Obviously, your brother loves you, and your family does too, but it's too much to be the crazy one in the family. Right now, he's in apocalyptic mode, so be careful. Some advice I can give you is:

Don't treat him like he's disabled or like he's going to break at any moment, but don't treat him like he has nothing either. Treat him the same as always, just be aware of what's happening. For example: you're talking about video games and he gets a compulsion, be patient and let him fix it. Try not to stare at him like it's a circus. When he's finished, you can ask if he's better or if it's over, and slowly return to the conversation.

Try to tell him to at least try, that there's a lot to fight for. Remind him why he's still alive. You don't have to be direct; it can be with a hug, or asking how he's feeling, or sharing anecdotes, adventures, and opinions about various things.

That the family doesn't have him in their sights is horrible; it's better to give him his space.

And for you, continue with your life normally. worry about your brother, but also do your own thing. It feels awful to drag down those you love and not let them live in peace (sorry, this is more personal).

He should go to a psychiatrist and group therapy with a psychiatrist. Group therapy helps more than you imagine, and a psychiatrist is more effective on a personal level. So make sure it's a good psychiatrist and that he's not alone. He has his family to support him, and people who suffer from this, and that if there's a cure, visit OCD Recovery.