ClearLight, I second others when they say to check your motivation as to why you want to break the news of the drinking to your sisters.
Although it sounds like a good idea now, you are one day sober and are about to lose your job. I have lost many jobs in my life and even though it wasn't due to drinking, those around me tried to seek blame and blamed the drinking.
Since you said your sisters are all that you have, tread lightly and I'd wait to tell them until you're at least 1 month sober so that it's not even in their mind that it is the cause for the job loss.
"The boy who didn't cry wolf because he was passed out drunk was saved by the sober ones around him. For it's the sober ones that truly know the meaning of saving and looking out for others." -- TastyCheez, 8/1/2015
Wait until you sober up for a bit before trying to get the gears in your head turning when it comes to finding ways to break the news to your sisters.