I'm so terribly sorry for your loss 😞 I am not a widow, but a 30 yo carer to my husband with an inoperable brain tumour. We have 2 children, one 6 months old, one 3 yo.
I hope you have family & friends supporting you at this time, you need to allow them to do so.
I can't imagine how you are feeling, even though every day I choke on the thought that I too will be there very soon.
Cuddle your baby, cry, and allow yourself to grieve.