Help with parents! (Needed)

hey guys so im 18 right now living with my mum in Australia where weed is still illegal. In the past she has caught me smoking a couple of times. The first time she was surprisingly cool with it and brushed it off with a slap on the wrist. The next time however she nearly tore the house apart. This time she is threatening to kick me out of the house when i have my final exams coming up soon. Backstory is that mum smoked weed once in her adolescence and had a terrible time, bought into all the propaganda and grew to hate Marijuana throughout her life while still smoking and drinking herself. She is the stereotypical pot hater, will happily sit on the couch smashing 3 glasses of wine and a bag of chips but its the will of Satan if i want to smoke a bowl and go to the gym. So right now i guess i'm just asking if anyone was in a similar situation and got around it somehow? Or what i can say to make it seem a bit better in the eyes of Mum. All help is greatly appreciated!! Sorry if this was a bit weird still at a solid [6] trying to sort my life out.