Sorry is so to little in a case like this. And it is always okay to cry shows that we are human and still care for another.
Keep those good memories of your friend in your mind as well as your heart and then he will live on forever!
Loss is very hard to take but with prayers and support from your friends here and over there it lessens the pain and some of the hurt.
Take care be well and visit your friend as you can all my best to you and him!