If Status Changes from ""New"" to (anything else), make ""New End Date"" today's date. Vice versa

Imagine 2 date fields. "New" Start Date and "New" End Date. Then imagine a Formula - Duration Field called "Time in New".

Now imagine that when a new record gets created, "New" Start Date is defaulted to Today's Date. Can anyone help me with this formula (explained in English). If the status changes from "New" to anything else, mark "New End Date" with Today's date. This would now result in a calculated "Time in New".(For my purposes say this equals 3 days)
For this next part, the key is that I want to retain the 3 day duration while also accounting for the possibility of re-entering the "New" Status, and accounting for the additional time. Now if Status changes from anything to "New", mark "New" Start Date as Today's Date. Finally when Status Changes from "New" to anything else, mark the "New" End Date with Today's date. NOW, add that duration from the previous time in "New" (3 days), to the new duration that results (say 2 days).
This is essentially trying to account for the possibility that a status is entered, and re-entered, without having multiple iterations of start and end date fields.