Help me find!

-modern world/ office setting
-female protag
-went back in time
-died because of car accident? Not sure on this bcus she had cancer or like she was terminally ill b4 she died.
-found out trash gusband qas cheating on her w her best friend
-best friend had red hair and the plumpest lips known to man omfg
-ml is like fmc boss or sumn has blach hair and also has a suster that helps our fmc l8r on