Try baby wearing. Seriously. Get a sling and strap that child to your chest, shirtless if you can, all day if necessary. It frees up your hands and that just gives you so much more mental space for all the other things you have to deal with. Let him nap in the sling. Also, I know co-sleeping is a controversial topic here in the US but it is the easiest way to get a fussy baby to sleep through the night.
If you still have any milk at all, try double nursing, where you nurse on both sides and then on both sides again in the same feeding. Also fennel, as tea or simply chewing the raw seeds, really helps with milk production. But if you have no milk left, don’t sweat it. Try feeding him shirtless as well, because the skin to skin contact may or may not help you feel closer to him, but it will definitely help him feel closer to you.
I have five kids and both sets of grandparents live far away, so I had to deal with babyland essentially alone for all of them. Do whatever you have to to get some time without them, even if it means leaving the house a disaster while you catch an hour while they are both sleeping to draw or journal or listen to music or stare out the window, whatever you need to do to get a little bit of mental clarity. I’ve been taking goldenrod tea, a cup every evening, and it really helps with that fuzziness and that difficulty with managing emotions. If baby is really pissing you off, just leave him in his crib for a few minutes and step outside so you can cool down. Even just a minute or two away from the crying can help you deal with it when you go back in to get him.
I hope this helps!