I'm sat here feeding my 9 week old as well. Luckily this time I just have a little PNA, but with my last child I had PND and PTSD quite badly so I can relate. It is utter shit and I'm sorry you're going through this.
Practical things that help me are DH having the baby in the evening until 11pm so I can sleep then and again in the morning for an hour from 6am. I don't know if you're breast feeding, I am, but when my husband has DD he gives her a bottle of formula so she's more likely to settle when he brings her back.
DD goes through phases of only wanting to sleep on me. Have perfected this as best I can with no duvets around us and a nursing pillow under my arms and her on my chest. I also kick DH out to sleep on the sofa so I can sit in the middle of the bed. Not super comfortable, but works if you're tired enough.
Colic is hard. I wish babies could tell you what was wrong. Try a thorough winding after every feed. DD was recently quite upset and it was constipation? Last DC had silent reflux, but had that from the start. Not sure it would start this late on. If all else fails I put the sling on and rock DD to sleep in that which nearly always works when all else fails. Can't sleep with her in it, but at least she stops crying. I then stand or sit on the edge of the bed to make sure I don't fall asleep. Can often transfer her out without waking her once she's in a deep sleep.
I hope you feel better in yourself soon. I felt so disconnected from my first child. Just going through the motions and wishing we'd never had him. One day I looked up though and realised I loved him. I don't know when it happened, it wasn't a big rush, just a slow drip drip, but I did. And now I love him fiercely and completely. I think it was looking after him, getting to know him and knowing that he depended on and wanted me despite all my failings that did it. Lots of
to you.