It's been a month since my friend passed, and I still feel numb...

My friend passed away a month ago today. I don’t know what to feel, say, or do. I really loved and cared for my friend. I act happy, preppy, and nice everyday, but all I think about is him. This will sound totally stupid I know, but I do it. Everyday I write him a letter telling him how much I love him and what I’ve been feeling and doing that day. Stupid right? I really want him back, and I hate not getting a call, or text, or something. I know I will never, ever get him back..and that makes me want to die even more. I regret not talking to him. I ask myself everyday “What would he have said if I replied back to his message?” I feel like I have to live with that on my head. I also have to live with knowing he liked me, but I was too scared to tell him I liked him back. Now that chance is gone. What do I do?