I'm so sorry to hear this OP.
I too had PND after the birth of my first and whilst I didn't have thoughts of harming him or myself, I felt as though I didn't love him, didn't connect with him, there was no bond. I didn't want him. I had tried for him for a long time, he was planned, loved, then I gave birth and my hormones went wild.
It was awful.
The change in me was also physical. My facial expressions disappeared, my mannerisms changed, the way I walked, everything. I was like a totally different person.
Because of this it was easy for people to spot. My HV noticed immediately and to her credit she managed to get me on a waiting list for therapy but I was bumped up because it was post natal. Maybe this can happen for you?
I went to the docs and they put me on medication.
I got better and you will too.
It DOES get easier but you won't believe it till it happens. I didn't!
Go to your Gp and your HV.
It's common.
It doesn't make you a bad mother.
Seeking help on Mumsnet shows you recognise this behaviour and want it to change.
That makes you a great mum.