I kind of understand where you're coming from with this.
It's been almost 5 years since my grandad died and i'm still "healing"
What your friends grandma said isnt correct. As has been mentioned previously, theres no time limit on grief what so ever. You do it in your own time. It will never stop hurting but it does get easier. I dont know how long its been since your brother died, but seeing as it was your brother i'm guessing you're hurting immensly.
As others have said, there can never be a time limit on grief. It may take decades or it may take months and either way, it's ok - it doesn't reflect on how much or how little you loved them, and it doesn't mean there's something wrong with you. Sometimes, people do expect you to move on more quickly than you're ready for, but that's their problem.
i think hazard said it all there :)
Some advice someone gave me:
I think it's important that you give yourself permission to grieve- accept your own feelings and express them, whether it's fear, hurt, anger, etc. Try and cope with those feeling the best way you know how, whether its through journaling, poetry, art, but just try and make sure you release them (in a healthy way) rather than keeping them bottled up inside. Build up a strong support network around you, don't try and go through it alone.
Take each day as it comes, don't try and rush things, the grieving process takes a long time, and some days are likley to feel better than others. Understand that things are likely to be disruptive for a while as you, your family also have to 're-find their feet' so to speak. Take control of the things that you can, but remember that there are things that you will have little or no control over, and you can't do anything about that, so don't focus on them.
Make sure you keep hold of your memories because they are now the most important thing that you have. You could make a memorybox or a scrapbook, with photos, written memories, trinkets and special things that remind you of your brother.