I know how you feel.
My Mum passed in Feb from alzheimer's disease in Febuary this year.
She was living in Perth Australia and I was living in New Zealand.
I last saw her late last year and she didn't even recognise me.
My Dad passed about five years earlier from Bowel Cancer. I visited him a few weeks before he died. I spent two weeks having superficial conversations with him about this and that. I should have asked him about how he felt .
I didn't. The last thing I said to him when I went back to NZ was "See you later" How stupid was that ? I didnt know what else to say.