Worst thing I ever did (as a mum)

Last summer, I turned 30 as well. My objective for the next decade was to become an organized mum. Not the one I've been until then, always tired, sometimes exhausted, running after my kids, being utterly unprepared for everything (like going out without nappies or water for the baby or coming to somebody's house without a gift). I had decided I was not young anymore and could not benefit from this kind look from others "oh, poor young mum". It was time for some change. It started pretty bad. I did the worst thing I had ever done in my life during the summer. Being at the beach with relatives, we split in 2 groups, the ones that come home on foot, the ones that take the car. My husband goes with the 2 elder ones, and I am supposed to go home with the 2 small ones and all the picnic and beach things. I bring all the stuff to the car, attach the baby, attach my nephew in the other child seat (while my daughter aged 2 had gone back to the beach playing), my sister in law gets in the passenger seat and I turn back, see that the 2 child seats are taken, I drive home. 30 minutes later, my husband comes home and ask :"where is Bouclette?". The sister in law and I immediately realize that we totally forgot her! My husband and I rushed back and found her at the beach in a police car. I think if we had not found her alive safe and sound, my marriage would have not survived this could-have-been tragedy. The conclusion I draw from this event is that I should never put myself in such state of exhaustion where I can not pay attention anymore.