I'm 56 and in all my years there is only one conversation I would like to redo and that was when I was 17.
My eldest brother was in another state helping his dad fix up a house. He called home around midnight and was going on about how I should take care of myself and a bunch of other stuff, he was mentally ill and it was obvious he had gone off his meds. He kept calling till like 3 in the morning and I was sick of hearing it and just wanted to go to sleep so I could make it to work in the morning.
So last time he calls he is going on for 15 min or so about "hey 1d10 don't worry about anything, dad will take care of it, my dad will take care of it" so I kinda snaped and said "good, can I sleep now? I hung up the phone and went to sleep, less then a hour later my mom wakes me up to tell me my brother killed himself.
I didn't go to work that morning, I didn't go to work for a year. I just went fishing. My brother loved fishing and always tried to get me to go but I didn't fish and never went with him. After the funeral I took his fishing gear and went fishing almost every day from dawn to dusk for an entire year.