Partner developing memory issues

Hello everyone, I am new to this site as I look for some information, advice, and support with my husband's changing memory issues. I have read many of the posts and appreciate the sharing of stories and the compassionate help provided. This may be quite long, but here goes!
My husband is 76, I am 74. Over the past three to four years, I have noticed his occasional unusual memory lapses, which I had hoped was normal, age related memory loss, though I was concerned. For instance, we have walked our dogs on the same daily route for many years, and several trees were cut down around the corner from us. We love trees and were sorry to see them go. A week later, I commented on how I missed the trees, and he said there had been no trees there. This was a very different kind of forgetfulness in that he simply had no concept of there ever having been trees there before. Life moves on, and occasional things happened, like forgotten conversations. But in recent weeks these incidences have become rapidly more common, almost daily, and my husband gets frustrated and angry with me as I try to figure out what is going on. A few days ago, he told me "Hannah's car is parked outside". I said " who's Hannah?" (we don't know a Hannah). I looked puzzled and after a few back and forth questions and answers, as he got increasingly frustrated with me, I realized he was talking about our neighbor Rachel, who we know well, socialize with, and talk to often during the week. When I asked if he meant Rachel, he looked confused and said, yes, it is Rachel...who's Hannah? Also I'm now regularly seeing forgotten conversations about anything from casual to important, forgotten by the next day.
I was able by chance to talk alone with his PCP, who was subbing for my PCP for a check up I was having. He asked if I wanted to get my husband in for testing, but I'm not sure if we are there yet. For one thing, he denies that has memory issues, and insists that I am wrong. It is also the case that this is not all the time, and he frequently has a better memory than I do. Some days are fine. But I don't forget conversations or the names of people in our close circle, or to get the chickens in at night, which he has done for 30 years.
I am feeling anxious and with a sense of dread as things are quickly changing. I have a lot of lifetime experience with dementia.
My grandma and mother-in-law both developed dementia and both suffered for 15+ years. I was not the primary caregiver but the daughter of one and daughter-in-law of the other, and was a support, shoulder to lean on, and compassionate listener for most of my 20's and 30's, and then my 50's and 60's. My husband was primarily responsible for his mother's care for the last years, although she was not living in our home. Both ladies followed a similar path, becoming verbally abusive and physically aggressive and violent, to the extent of causing injury to family, caregivers, and other residents in memory care. It was indescribably hard. And I know you will know this.
My support is limited, our few remaining friends are older than we are and are having significant health, and beginning memory issues of their own. They need our help. We are emotionally close to our daughter but she is 400 miles away with a new baby, and I know this is not her burden to bear. I know I need to learn to accept what is happening, but the realization is only just hitting me, and based on my past experiences I am feeling stressed and terrified.
So that is my story. Thank you for reading and listening. I so appreciate that you are here.

J.