I have definitely btdt. There have been days when all three of us were sitting on the floor crying and I was counting minutes until dh got home.
Is a video for the toddler while the baby naps an option for you? I have done this sometimes on tough days - doesn't get me any more sleep, but it does give me a few minutes to myself, which can help me recharge enough to get through the rest of the day.
Other than that, I try to just prioritize to the max on tough days. I figure at the end of the day if the kids are clean and fed, I have done a decent job, and tomorrow is another chance.
I hope your day gets better.