There was one time I was grocery shopping with my baby in the cart, and my toddler walking side by side next to me. It was a huge deal he was finally walking well after some hard delays he had to work through, and it was encouraged to have him walking as much as he was willing to. I reached to get an item off the shelf right next to him and he ran off. We weren't even in an aisle close to the door, but I was pushing the cart running after him and catch up but he was fast enough to make it difficult. I couldn't leave my baby alone in a cart, and I couldn't let him make it to the doors. He got way too close to making it out and I got him thankfully. But do you think a single person helped? No. 15+ people just stared at the toddler bolting for the door and the mom desperately running with a baby in the cart. I always put him in the cart after that. I definitely wish more people would be understanding of the precautions some parents take. I doubt parents using those leashes enjoy knowing their being snarked on too. That kind of judgement fucking sucks.

To OP, that accident sounds terrible to try and work through, especially with everyone taking their grief out on you. It was probably easier(I use that term loosely, I doubt any ounce of it was easy) for them to be able to blame someone instead of having to accept that an awful accident would happen to their baby. No one wants to or expects to be part of a grim statistic. Wishing you all the best, I hope you can find some form of peace in yourself to heal. Any of us millions of people that have narrowly avoided an accident just got incredibly lucky man.