There is one lie you should always tell while grieving and maybe during other hard times too. “Fake it ‘til you make it” is not just a clever cliche. There is victory behind that advice. I haven't researched it, but I’m thinking there has to be some science too. And while not strictly meeting George Washington’s moral code for axes and cherry trees, this is less a deliberate lie and more an assumed attitude.
There are moments during loss when it is acceptable, even healthy, to just bow to the grief. But at other times and for the greater good, I suggest you give yourself permission to be less than candid. In the middle of certain faith that you’ll never ever again be okay, look in the mirror and say otherwise. I know you know you don’t mean it. But say what you don’t believe. Practice being an impostor in your own life. When you aren’t, you won’t, and you can’t, then say "I am, I will, and I can." It takes a while, but eventually, part of the lie will become part of the truth, and part of your life will regain part of its worth. And the best part comes when you finally feel good enough to congratulate yourself for the good lie. There is a real honesty in that.