How are we talking to our kids about cannabis use - ours, not theirs?

My daughter is 11, on the spectrum, and insanely smart. Like off the charts IQ, national honor roll, all that. She has very strong ideas about justice, is a rule follower, and views almost everything in black and white terms. She is absolutely anti smoking. Her grandma (my mother) smokes but no one in our home does.

Her father and I got our medical cards about 5 years ago. She's spotted my vape pen a time or two but I've been able to keep it simple and say it's "mom's medicine" and we move on. But it's starting to feel like we're gaslighting her.

She was hiding under the bed earlier when I came out of the bathroom, and she saw me take a puff. She asked me to promise that it's not nicotine, and I reassured her that it's prescribed by a doctor. But I feel this pull to be more forthcoming with an answer, to not hide it because hiding it makes it feel wrong. Any fellow moms out there who have some words of guidance? When and how do we talk to our kids responsibly about this?