I agree with so much of what's being said here and your sheer exhaustion screams out from your posts OP, I really feel for you. Your DP is not supporting you and that makes what is already a hellish time for you even worse, it must be incredibly lonely and you shouldn't be having to find mental energy you don't have to fight your corner with him on top of everything else.
There's been a lot of wise advice on this thread, NapQueen's list of things your DP should be doing, all of LRD's post and the numerous posters saying your breasts, your decision and that whatever method of feeding keeps both mother and baby happy and healthy is best. I can't add much to that but those posters are absolutely right and you mustn't let your DP make you doubt it.
The only advice I can give is that you need to resolve the issue you have with DP because you can't carry on battling through each day on no sleep, no time for even the most basic of things for yourself, no respite and battle DP imposing conditions which make this even harder for you on top.
What you decide about feeding has to be just that, your decision so we need to find a way to make DP see that and support you instead of fighting you. How you do that depends on the dynamic of your relationship I suppose, in my relationship it would likely involve me having a bit of a meltdown and letting him have it full force that I was at breaking point, that it was coming down to a stark choice between formula and my mental health and that he needs to decide whether he's going to support me or contribute to my decline. It baffles me in situations like this how someone can suddenly show such lack of care for the woman they chose to have a child and a life with.
I don't know if that would work for you with your DP OP, I know my DH would react to it with deep shame that he'd been so blind to my needs but only you know whether that's what's going on with your DP or whether there's a deeper problem.
I hope you find a way forward and that things get easier really soon 