I did it so I know how you feel right now. It is quite intimidating being the sole person in charge of an infant and an under two. It is objectively a big deal, you are not imagining that. But with real, material help from dh you can get through.
Please do not expect too much of yourself or the children. Slow right down. Routine can be a great help in the sense of a rhythm for the day, the predicatability of which children respond well to. At this age they are not looking for excitement, familiar is good!
DH can and should do a lot to help. For example, take over all food organisation (buying/ordering, putting it away, cooking for the next day in the evenings etc), laundry, and a tidy up before bed so you have a reasonable space to function in. It may read as a lot but if done more or less everyday it should not be too tasking. Every meal cooked in the house should be doubled or trippeled in volume and frozen in portions. This is a huge help.
I advise strongly that you establish this in detail before he goes back as he will quickly forget the grind (read a million threads on Mumsnet!). He will also have never done it solo, and will therefore not really understand how draining it can be. I also advise NOT discussing it in terms of help you need but rather in terms of what needs to be done and his share of that. That last bit is very important.
It will slowly evolve. Setting your day up in blocks like they do in school can really help. Feeding both at the same time is wonderful when you get to that point.
Fresh air every day is really good for you and the babies if you can. Even 10 minutes. Don't underestimate how much a child can enjoy mucking about outside with the right clothes on, it can be a real tension buster.
At somepoint soon take a fewvhandfuls of toys from the two year old. Put them in bags. When the going gets tough you can produce a "magic" bag - that one worked wonders for me.
A bath with all three can be good if you have a tub.
Don't be hard on yourself OP. It is a tricky time - on the one hand it can be lovely and joyful but on the other exhausting and lonely. I felt like a failure many times in that period but looking back now I wonder why I expected so much of myself.
Good luck!