I do think in part it's hormones (and sleep deprivation) but that doesn't in any way diminish the realness of what you're feeling or the risk of PND.
It's really important you keep talking.
To your DH, your midwife, your GP etc because it's hard. I remember crying in the dark that the babies only cried because they hated me. Happy 10-16 weeks pp, not.
.
It does get easier, they feed less and poo less, they puke less and need redressing less. But it takes time. And help.
And space.
As soon as you're ready to have an hour away from them, you leave them all with DH and you just go somewhere and be alone. And when you're ready for longer, you go somewhere and be alone for longer. Or see friends. A movie. Whatever. But he's a grown man and he'll cope. Because he has to for your sanity.
Get yourself a decent bag, preload it with nappies and wipes. But the premade bottled of milk so you're not dicking about with powder and hot water. If you forget something or someone pukes on the last outfit, it's fine. We've done a few emergency visits to charity shops for emergency clothes. Some last minute pop into a shop to buy any nappy vaguely the right size.
Take any help offered. Ignore any comments from mother of singletons about how it's only as hard as.... Try to procure some real life twin friends. Ignore any looks in shops or buses etc except ones that convey respect and compassion. Ignore idiots.
None of us choose our children, we just try to get pregnant. I had one with a severe congenital defect who fought for life on and off for 18 months. I didn't choose him. I didn't choose to be a mom of a "special" child and god doesn't give those babies only to special mothers. But he's mine, I love him and I wouldn't change him. I didn't choose twins but that egg split, and there's no going back.
They're 5 now, and they're a handful. But so are my friends kids. They have the cutest bond and there's literally nothing sweeter than their love for each other.
You won't get through this because god only gives you wh as t you can handle or because mother nature picked you especially. You'll get through this simply because cwe just do, sanity not intact, but workable. You'll get through it by leaning on your loved ones for physical and emotional support. By being honest with those around you and getting the help you need. By not being bullied into being everything to everyone all the time.
My presents off DH are usually about me being alone. Theatre, Spa day, cinema pass. He knows I need that.
You matter too.