My Cousin Is Saying My Grandmother Was Pressured Into Adding Me To Her Bank Account Before She Died

Location: Arizona

My grandmother passed away a while ago and this has turned into a mess I really did not expect. About a year before she died, she added me as joint owner on one of her checking accounts. It had around $110k in it when she passed.

She did this because I was the one helping her with random stuff, groceries, doctor appointments and basic stuff around the house. She was 76 but still pretty sharp mentally. She had mobility issues and needed help getting around, but she was not diagnosed with dementia or anything like that.

After she died, the bank told me the account passed to me as the surviving joint owner. I used some of it to pay for the cremation, clean out her apartment, and cover a few final bills. The rest is just sitting in savings.

My aunt, who barely visited my grandmother the last couple years, is now saying the money should go to her. She claims I pressured my grandmother into adding me because I was the one taking her to the bank that day. She also said her attorney is going to file something for elder financial abuse if I dont agree to split the money with her and my uncle.

I did not force my grandmother to do anything. She told me months before that she wanted me to have that account because I was the only one actually helping her. The bank employee spoke to her alone when the paperwork was done and everything was signed in person.

My grandmother did have a will, but it mostly talks about personal belongings and says the rest of her estate goes equally to her two children.

Does my aunt have any real argument here if the account was joint with right of survivorship? Should I be getting a probate attorney now, or wait until she actually files something? Also, should I avoid spending any more of the money until this is sorted out?