My baby's dad makes me feel like a jump off

So me and my baby's dad just got into a little argument about money. So we just got a new house that cost $400 more than where we stay at now. I did agree to pay $300 a month since I'm living there also. Our income is totally different I make around $500-$600 a month and he makes around $5,000 a month. So okay I've paid $800 so far in doctors bills for the baby and also bought her everything she will need (crib,changing table,clothes,diaper bag, two car seats and two strollers etc) he has bought a box of diapers and two pacifiers. Which I was totally okay with because he was currently paying all the bills. Okay so now the $300 is due for my portion of the rent and I have to make a final payment for the baby bill which is $295. So since that's my whole check I asked him could he pay for it. He laughed and said I knew it! He's implying that since my name is on the lease I should pay too. But I just don't get it I'm not going to have enough, I'm 9 months to remind you and he just makes me feel like I'm just a jump off and don't want to help with anything. I mean I provide food in the house, I've bought the baby stuff and paid her bills I'm just tired, how would you approach the situation? Also my mom sometimes helps me with bills here and there but I asked her could she pay his car payment which is $400 because at the time he was sick and couldn't afford it because he took time off. So the money I could get from her is used up because of him