After my baby died, someone told me that this is the worst thing that will ever happen in your life. I believe that's true. It is the worst and most difficult thing you will ever go through. But you will get through it. It is very hard, but it will eventually get easier.
If you have friends who are not being supportive, now is not a good time to be spending time with them. If you need to separate yourself from them for a while, that is OK. You need to be with people who want to help you through this.
Here is a good web site about grief: http://www.recover-from-grief.com/index.html
I found it very helpful to learn what I could about the grief process so that I know what things are normal. It may be helpful to encourage your friends to learn about grief as well. Nobody can understand unless they have had a similar experience, but your good friends will want to do what they can to help.
You need to give yourself time to grieve. No matter what anyone else tries to tell you, you must work through your grief on your own schedule. Nobody can say when you should be back to normal.
I encourage you to feel your pain and express your emotions. If that means just sitting down and crying for a while, that's OK. Drinking to numb your pain may help temporarily, but not in the long run. You need to process your grief or you will never feel better. That being said, your grief is your own; nobody can tell you how to grieve for your child. The grief process is different for everyone. It may take you much longer than your friends expect.
I am so, so sorry for the loss of your precious boy Isaac.