I need to know how best to help him and communication of feelings isn't a family strong suit. My mom passed in July after 6 year battle with lung cancer. I don't know when he wants/needs to be alone or what else to do to help him. He knows I am also very emotional when it comes to my mom's passing so he tries to protect me too.
Look for signs that he may be depressed and find things he likes to do. Can he go on outings....these seem to cheer up my Mom. Does he have hobbies or people he likes to visit. If you are both greiving, it would be great if you both got out to be around other people.
When and if he needs to talk about your Mom he will bring it up..just wait for those cues. It may still be really painful for him to talk about your Mom and, as you said, he may think he needs to be strong for you. When both people are in pain, it is hard to think clearly.
Time is a great healer. I think that it is a very human thing to think that when we stop greiving for someone they are somehow forgotton. I think that is why we greive for so long over a loved one.