How to comfort your sibling?

My eldest brother has been depressed ever since he fought with our parents. For the context, he's gay and been living with his bf for quite some time and recently he comes back to our house just to get berated by our mom. He's open with his sexuality and I looked up to him for that, however, our parents especially our mother has old people mindset.

He's a kind person and gentle, never raised his voice but a week ago, for the first time ever, he raises his voice at our parents. And today, his bf called us siblings saying he been holed up in their room– eat and drink when needed.

He has a history of self-harm and I'm scared he doing it again, and losing him. He one of the reasons, us siblings still here despite the trauma our parents gave. But I don't know what to say to make him feel better, to make him realise that we accept him for who he is. I never good with words– but I think words is the most things he needs. So can you guys please give me advice on what to do at time like this?