One-shot. Based on HoME events.
"In the morning the host was mustered, but of Fëanor's seven sons, only six were to be found. Then Ambarussa went pale with fear. 'Did you not then rouse Ambarussa my brother (whom you called Ambarto)?' he said. 'He would not come ashore to sleep (he said) in discomfort.' But it is thought (and no doubt Fëanor guessed this also) that it was in the mind of Ambarto to sail his ship back afterwards and rejoin Nerdanel; for he had been much shocked by the deed of his father.
'That ship I destroyed first,' said Fëanor, (hiding his own dismay). 'Then rightly you gave the name to the youngest of your children,' said Ambarussa, 'and Umbarto "the Fated" was its true form. Fell and fey you become.' And after that no one dared speak again to Fëanor of this matter."
- The Peoples of Middle-earth, The Shibboleth of Fëanor - J.R.R. Tolkien
She knew his spirit had returned even before news reached the shores of Valinor.
Then she had wept for her dead child; but no less did she grieve for the six sons who still lived. Umbarto's death had been swift and fiery, wrought by the careless madness of his father. Yet his soul, at least, would be preserved; the flames of Fëanor's madness had not yet scorched it. For the souls of her other sons – she prayed. It was an evil thing they had done, and though she might hold them blameless, driven as they were by the powerful will of their father, she knew the Valar would not. And what lies ahead for a soul thus condemned? As Melkor had robbed Fëanor of that which he most cherished, Fëanor had alike robbed her. Her children would now share in his curse. By their love, he had driven them to acts of hatred.
Before he departed, she had spoken these words to him:
You will not keep all of them. One at least will never set foot on Middle-earth.
His fey laughter still rang in her ears, a bitter sound in the ears of the wife who had once loved him. When she looked upon his face then, she saw the shadow of Melkor. Fëanor, once the brightest flame among the Children of Ilúvatar, had succumbed to the dark influence of the one he named Morgoth.
He had left her with these cruel words:
Take your evil omens to the Valar who will delight in them. I defy them.
And so he did. Later, as the Valar mourned for the marring of Fëanor, as even Manwë Súlimo bowed his head and wept, Nerdanel shed no tears. When his fiery spirit flew back to Valinor, her heart had long turned cold to him. She had no pity for his soul, which would rest at the mercy of the Valar. But for her sons, she wept.
Fëanor and Nerdanel's words to each other [italicized] are taken from The History of Middle-earth: Peoples of Middle-earth by J.R.R. Tolkien