The last post was so thoroughly... looking for a fitting adjective here... well, "amazingly insightful"... that I am leaning towards recommending that you at least postpone the divorce for now.

Because - see you are saying that he is more likely to die if you divorce him now, so it makes sense to postpone.

Also... your mum will eventually die. I am sorry to say that and I am sorry if it hurts you, but humans are mortal.

Since one of the things that anchors you to this guy is your mum's situation, if and when she dies, you will reconsider the divorce/no divorce options THEN.

Just reminding you of the harsh reality of humans' mortality.

On being gaslighted - I salute you for that level of awareness. I was gaslighted for years, by my second husband when he was my husband, and then by him for a few more years when he was my ex husband (his choice) but still continued to control and gaslight me. And, my friends told me that he was gaslighting me (actually urging me to watch that movie), but I did not believe them.

Ultimately, I did realize that he was gaslighting me, and regained my confidence, sense of humor, logical mind, sanity, and all the rest of that. But I was not living with him at that point.

To the extent that you are being gaslighted and have enough insight to realize that you are being gaslighted, you are a super human.