It's the hardest time. But it really won't last forever. Try to create structure to your days. I used to take DC out twice a day every day, just so we didn't get stir crazy, to keep the house reasonably tidy and to get some company. Once every day was a planned event - soft play, church playgroup, mums and toddlers coffee morning, toddler music or tumbletots. And once a day doing our own thing - going to the park, to the supermarket, city farm, or just for a ride on a train or bus to see the world. It might sound tiring, but once you have a bag packed for any emergency and a few snacks, it's way less stressful that being stuck at home trying to keep them occupied.
Then they watched tv while I made tea. After tea we'd play then both and bed.
Keep adult dinners very easy: traybakes, pasta with simple sauce, the occasional healthy-ish ready meal, straight from the freezer.
Tell DH you need a few hours each week or you'll go insane. Get him to look after them for a 4 hour block of time every weekend while you get hair done, go to the gym, see child-free friends, go shopping, update your CV or lie somewhere sunny and read.
Soon they'll both be at nursery and you can go back to work.