Feeling absolutely alone through this new mom phase

Despite a rough start, my baby dad and I decided to have the baby and I was promised equal partnership with respect to responsibilities and finances from day one .. I trusted! And now, it's been almost a year into that promise, and an absolutely awful pregnancy filled with zero financial contributions from him + all household work done by me .. followed by premature birth of bub at 26 weeks, bub at NICU for 111 days + me trying to manage household, bub at NICU, expressing breath milk, brief period of full time work to manage finances and moving places ---- all of it was pure torture and an absolute financial rip off .. every single article / object at home , that of bub's , insurance, hospital bills, etc -- I paid them all.. including loaning money when he needed it .. Well, he did pick me up and drop me off at the hospital visits.. Right now, it's been 3 months since my bub's home, and I have again started working full time , I work night shifts until 2.30am., I come back home and look after bub, , I cook , I clean.. I am stuck in a loop.. Every time I brought this up, he promised to make amends and things never happened.. And now, after having done all of this, he wants to finally pay half the rent, and that's it. He doesn't wanna pitch into anything more.. I thought I honestly cared for him , I trusted him immensely, and somewhere in between - fell in love with him. I haven't been in such a bad situation before.. He isn't home much either, but when he is, he is loving towards bub. He doesn't give a fuck about my existence , my wellness.. I complained of chest pain 2 days ago, and his reply was ' so, what am I supposed to do' ... I am stuck because I don't have any other support system.. I am in between a PhD thesis submission and final graduation - and in between visas as well.. so I can neither travel back to my country nor get a decent job to live by myself.. I have even had thoughts of leaving..just leaving the world altogether. But then, I see my bub and breathe through it. I don't know how much longer I can do this for.. I feel so numb from inside.