Has any parent had to make to hardest decision ever to let your child go?

I had a baby boy born 10 weeks early due to preeclampsia and after 26 days my husband and I had to make the hardest most toughest decision ever to let him go. I want to know if anyone had to go through the same thing or something similiar? I have talk to people who have had stillborns but its not the same, in the aspect of losing a child yes but thats all.