My husband has had mixed dementia for over 9 years. What you are describing is not uncommon. Driving is one of the most difficult issues we face. My husband drove a semi truck and trailer for most of his working years and for him to be told that he shouldn’t be driving was terrible for him. He denied it over and over whether I told him the doctors have said it or pointed out other reasons like cataracts or his painful knees. He’d just get angry and say that the doctors don’t know him or whether or not he can drive. We solved some of it by having our daughter drive. He seemed to be ok with that. I bought a new car in the spring and haven’t let him drive it. I hurry to get in the driver’s seat and he’ll get in the passenger’s seat reluctantly because he still likes to get out. He’s not happy about it but it’s getting better. I had a kidney transplant in 2018 and am doing well. I wish you the best.