Dementia Grandmother Wants To Press Charges Against Me (17f)

I’m 17 and homeless, so me and my dad have been staying with my grandmother who has dementia. We didn’t realize how bad it was until we started staying with her, and have been acting as caregivers. If she lends me money or lets me use her debit card she forgets, and accuses me of stealing and calls me loads of nasty things. This also happens if she has money and misplaces it somewhere (she hides it because she’s convinced people are coming into her house and taking it, then forgets where she hid it.) Anyways, she doesn’t like using her card but if I ask permission when she’s in a good mood, she will let me use it for small purchases. Unfortunately when she forgets that I asked to use it, she goes to her bank, sees her card being used, and says someone is stealing from her. The bank believes her and they are doing an investigation and have deactivated her card. When she was saying someone was stealing from her card I didn’t realize it had been ME, and now I don’t even know how to tell her and explain she gave me permission without her freaking out on me and calling the police since she doesn’t remember it. I’ve just been accepted to my dream college and will be going out of country for a year in September, my life is finally turning around. Will I be arrested??? In hindsight I shouldn’t have asked to use any of her money knowing she has memory and agitation issues. That’s completely my fault. So far my current course of action is just going to be telling her the truth, though I know explaining to her that she said yes to me will just make her agitated and begin berating me. I’m also worried she’s going to lie to my family members that I really just stole the money on her card, and I’ll be shunned within my family. I’m so stressed and don’t know what to do, will I go to jail??