We had a similar experience with my dad. (Asking about moms past boyfriends, they had been married 59 yrs at the time, insisting I was trying to put him in a nursing home, actually I got hospice to come to the house) We decided it was either lack of oxygen or hardening of the arteries in the brain. It was weird how these things happened, one minute all was well and the next minute, Katy Bar The Door, the chit was on.... I did notice there was not so much of this while he was using his oxygen.
Keep your chin up Julie.. Prayers and thoughts with you 2.