According to reports, the couple's 10-year marriage is effectively over, with a separation agreement expected to be drawn up shortly.
"She wants out. Neither she nor Charles are interested in counselling or trying to save the marriage," a source said.
Another friend added, "This is not how Nigella imagined her marriage might end but she realises it was the tipping point. The marriage has been under strain for some time but the choking incident was the end.
"If anything it is a relief for her that it could all be over very soon. There's a sense she has already moved on in her own head."
Lawson, who has moved into a rented Mayfair apartment, was spotted without her wedding ring on a day out recently.