My DD died in similar circumstances (suspected SIDS) in September. I remember the shock and utter devastation and am so sorry you are going through this.
4 months on, I feel like nothing is any better and some days I just sob my heart out. But when I look back at how far I have come, I realise that time has made things slightly easier. I don't cry every day. I can eat again. Going out is still hard but I am doing it. You will do all of these things too.
Everyone handles things differently. Take your time and be as selfish as you need to be. What matters is your family and you. Take comfort from those you feel safe around and prepare to ignore the insensitive comments from people who just cannot find the right words. Your children will get you through. Don't be afraid to cry in front of them as they need to know that it's ok to be sad and show emotion. You don't have to be strong, you don't have to do anything.
Things won't be the same but you will find ways to honour and remember your son. You will always be his mummy and no-one can take that from you.
Concentrate on getting through each day. 4 months on I can concentrate on each week. Sleep when you can and keep drinking.
I wish no parent ever had to go through this and I am so, so sorry to read this. Mumsnet offered me so much support and I hope it can do the same for you.
Sending so much love to you and your family.