Coping with life's major issues is so exhausting, it leaves nothing for all the rest that mere living requires. I'm older too, much closer to the end of my life than any other marker. Right now a lot of my physical problems are hitting all at once, & I did have a day when I wanted it all to just end now ... both of my parents went quickly, why not me? I've had those days before.
I'm sorry you're holding so much pain. Your measure may be more than mine, IDK--but I do know the feeling at this point in life of not having options ... of knowing some of this you brought on yourself ... of being at a point of no return.
I'm glad you posted, because I'm sure you'll find many can respond with full understanding.

There is no consolation to offer, but I understand.
Roadie