I am so very sorry for your loss.

Please, please, please do not try to hide the fact that you are hurting inside. Your family and friends NEED to know that you are not coping well so they can help and support you through this tough time.
Open up to them, that is why they are there.
You are going through a very difficult time, and there is no reason to down play the emotions. Feel free to cry, vent, scream. Let it out, trust me, it helps!