Juan love, you're being far too hard on yourself. It's far too soon to even be thinking that you need to be crying less, doing more, making decisions etc. All you have to do is get you & the DC through the day. That's it. That's a successful day, that's plenty. M thinking a day in bed was a wasted day was fine, because you were all there, he was wringing the life out of every day - this, this is different. You need to 'cope' for a while and look after yourself & if that means retreating to bed, then so be it.
I couldn't stomach the smell of food either, which was another reason the tiny sandwiches were good.
DD's boyfriend sounds like a 'keeper'. I hope he's as lovely as you portray him.
I was crying reading about you going into M's treatment room to get the drugs & seeing everything in situ. The cheese he bought in the fridge...it just cuts right through you doesn't it. Several years on my Dad's slippers are still where he left them (they do get lifted to hoover 😁) and his jacket is still on the peg in the hall etc. We see no reason to move them.
At first I didn't like having dreams, but now I treasure them. It hurts waking up, but I'll take that pain for the moments where it feels like he's stilll here.
WRT the food , I think that's a good reply to your friends. Whatever gets done, will be 'the right thing'. It's about the worst time in your life to have to make decisions, yet you have to make so many decisions. Delegate any you can.
Please don't be so hard on yourself, nothing you are feeling Is pathetic, nothing. It's normal. Don't pressure yourself to stop crying, or 'do things' or 'get on with it'. Take the time, grieve without guilt, be kind to yourself.