It's difficult. Bereavement has alot of similarities to depression. It's a totally normal reaction to losing a loved one. Our minds have to process our loss and that involves quite a journey of emotions. There's some information out there about the different stages of grief, they dont come in an orderly fashion though - some 'stages' can happen a few times, I went through a couple of stages of not being able to sleep, just being awake between 2 and 4/5 like clockwork
It's really important to try to look after ourselves,do your best to eat, and eat healthy stuff where you can, try and get regular sleep, get out for walks etc, see people. Sometimes we have to be gentle with ourselves and just rest a little bit. Do you have people you can talk with? That's so important for helping us process our grief - and a reason this forum helps so much. If feeling shy, can always try journaling - writing out your thoughts etc in a diary can also help us process it and make sense of things.
Make sure you take notice of what you are achieving. On particularly bad days even if its only getting out of bed and dressed, its all steps forward. On bad days concentrate on baby steps. We used to have a '5 a day' thread, where you have a post and each day you try to notice and add something good/achieved or grateful for. That could be anything, big or small, on bad days could even be you had a good cup of coffee. But in time it gets easier to get up to/find your 5. You could try that perhaps? (I still do that each day in my paper diary)
All that being said, it can also easily develop into depression. There is no shame in needing support, and there's a variety of support available, such as medication and counselling. The medication won't take away the grief but can make it easier to cope. I think bereavement counselling is usually offered after 6 weeks has passed (I'm guessing due to such heightened emotions at the start of grief), but can certainly enquire and pursue at any time. Pop and see your Dr and have a chat - Dr's are very supportive
Xx