Covert Narcissist going wild

I am in a relationship with a woman for nearly 20 years. She has always exhibited narcissistic traits(lack of empathy/ intimacy/ abuse) Recently it has escalated into heavy drinking / cheating / excessive demands/ spending out of control/ drug taking and lying about everything
. She has now said she is questioning the marriage and is maybe looking to get out. She has never worked and is living in a dream world where she is the star. I am currently trying to hold things together with work , house & kids while she has split to the USA to think things through !
Any advice would be welcome ?