Bad news.....

Well I spent 5 hrs in the er last night. Just to be told I was having a miscarriage. 2nd pregnancy, 4 weeks along, and it's just gone. Idk how to react. I feel like a piece of me is missing. I guess if you go off ovulation I was only 2 weeks, but my body was already changing and after you have 1 child your body knows. My 3 yo son has been looking for the baby already and now I have to tell him that there's not gonna be one. This is my first miscarriage, any advice on how to cope with it.....