1st off, I am sorry......
My DD just lost her BF of 3 years, it happen in March, he actually died of an asthma attack. It has been a rough year and it will be, all the 1st are very hard, he past away on the 3rd, so the 3rd of every month is hard, he died on a Thursday, so Thursday's continue to suck, they declared him dead at 12:11 pm, so another hard time.
Just be there, try to talk to him as much as possible, grief counceling is a big help. There is a big defference in reg counceling and grief counceling, they are trained on what to say and what not to say. People will say horrible things thinking it will help, try to explain that to your brother.
We got tired of hearing "You will find someone else" sorry my DD is not crying because she thinks she will be alone for the rest of her life, she is crying because she lost someone that she loved very much. Calling a stage may also be hard, or saying he will move on may be hurtful and not comforting.
Just being there to listen, give hugs or just sitting by his side is what is helpful. They next year will be a hard one, people heal all very different, it may take a few months, or a few years.
Odd enough my daughter is handeling it better then I am right now, I loved him like a son, Christmas was hard on me
Sorry I didn't have to much to offer, but hope this helps.......