I wonder if you're still reading this OP, so much hostility for someone struggling as I'm sure the vast majority of us have - anyone here saying hand on heart that 8 weeks after their first child being born they were all "oh, super loving my life!" is lying. The first three months with my eldest were the longest of my life! Lack of sleep, lack of rest, lack of that-human-i-used-to-be (who had been replaced by a shit-wiping, milk-squirting, scream-hearing automaton). It's fucking hard!
On to the situation. When you say financially broke do you mean you have no extra money, even for non-essential foods like basics range biscuits, or do you mean you will not be paying your rent/bills at the end of this month? Because I think the former feels desperate while the latter IS desperate. I was pretty bloody anxious 2months post partum and they would have felt equally bad. But if you can actually continue to pay your rent and bills and eat then maybe you can be reassured that this time will pass.
The PhD thing is ridiculous IMO. I know several WOMEN who did PhD's after having kids and they wrote up entirely at weekends while their OHs (who worked full time during the week) took the babies out all day. Your husband definitely COULD be a sahd and still finish his PhD no bother, albeit in a slightly longer timescale.
What to do about this is hard though. Not liking being a sahm after 2 months doesn't mean much, it's a fucking massive shock suddenly being responsible for the complete care and wellbeing of someone else. I bet if you ask junior doctors 2 months after graduation if they enjoyed and were good at being doctors yet they'd say no, and THEY get to clock off after a shift! That is not to say your feelings today aren't valid, just that they may change massively.
Your comments about sacrifice remind me so much of myself at that stage - I felt like the me who I had been was completely gone, utterly eroded. I couldn't cook or read or shit without the baby needing something, I was shell-shocked from the change in my life (i had been the higher earner in my relationship up until giving birth too). I did feel incredibly bitter about being the woman and lumped with it all. It wasn't that he didn't join in caring (though he didn't much) it was that the buck stopped with me, always always. I was always the one expected to do or fix anything he wouldn't/couldn't/didn't. It was exhausting and felt very unfair.
I can't advise about the return to work, my relationship fell apart completely and as a single parent I would have had to put her into childcare for 49 hours a week to return to my job, and would have been slightly less well off than on benefits. So I went on benefits, eventually she got older, I picked up some flexible freelance work to do in evenings and eventually met my DH who I have two more DC's with.
You sound like you're feeling so desperate, I can't believe the judgy crap people have felt legitimate in posting! I can't tell you what to do OP. YANBU, and many many of us have felt as you do. I can't tell you how to force your DH to shoulder his share, or how to work around childcare so that your working brings the maximum benefit to your family. But I can say YA DEFINITELY NBU, whatever you end up doing will be the Right Thing for your family and, most of all, this time will pass, the person you were will re-emerge, life will not feel like this forever. Best of luck.