I'm not sure if this will help but I felt very similar to you after my first was born. I even ran away one evening for an hour and only came back when I realised I had no phone or money.
You are not alone. A lot of mums feel like this. Be frank with your husband and tell him you need more help. Give him tasks to do, like sorting the pets. Tell him you're having an hour to yourself and run a bath and chill. This baby is as much his as yours.
You are not a bad mum. The fact you care enough to worry about it, shows you're a good mum. And as much as it doesn't feel like it now, you can get past this feeling. My son is nearly six now and last night he woke up, I went in kissed his head, cuddled him and he told me I'm the best mum in the world. He may be a little limited experience wise on that, but I'm taking it! It now seems a lifetime ago that I wanted to run away.
As much as I hated people saying this to me, it did get better with time. My son grew up, became more interactive, and dare I say it, more interesting. There was less repetitive routine stuff and I got more time to myself, which I think is really important for mental health.
Back, five and a half odd years ago, I was diagnosed with severe PND. We have something called the Crisis Team here in Gloucestershire. You can ring them and they can offer support. We also have a perinatal mental health team, which your health visitor should be able to put you in touch with. Finally, there's a local support group here for mums here, called Shine, who offer a chance to talk to other mums who are struggling (there's a lot of us) and therapy through craft whole someone else watches your baby. I'd ask locally if there's something like that. Or just get yourself something simple to pick up and do if you get a spare ten minutes, just so you've done something not baby related.
I wish you all the very best. PND sucks big time. But, from afar, I think you sound like a great mum with a lot on your plate. Kick your OH into gear and don't be afraid to ask friends and family for help if you can. Virtual hugs
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