Unrelenting Saddness

It has been two months since my husband of 30 years died suddenly from a pulmonary embolism while he was filling the bird feeders on our deck.
Since then my life has turned upside down and inside out..We have a full size labradoodle who is staying with my daughter because I can't be home by myself...big empty house that I am trying to sell.  I spend weekends with her and weekdays with my son and his family...living out of suitcases.
I wish someone would give me a recipe for how to do grief...I want to know that this will end; but I know it won't. Some days are better than others, but they're all bad.  I fell like I am holding in a lot of feelings, but that if I let them out, they'll take over and literally consume me.  I feel like that if I let myself start, I'll never stop crying.
My daughter says I need to give myself permission to feel what I am feeling, but it feels too big to deal with all at once.  Is it ok to just let in a little bit at a time?