Burnout is real and I'm in it

Current situation:

• Work: insane deadline, understaffed team
• Home: wife's mom visiting (in our guest room)
• Kids: 5, 7, both need new school stuff
• Me: running on fumes

I haven't had a day off in 3 weeks. I'm snapping at everything, forgetting stuff, just generally a mess. Wife keeps saying "it'll pass" but honestly I don't think I can wait for it to pass. How do people actually step back and breathe?