I'm jealous of my fiance.

So, I'm engaged to this guy that I have been with for almost two years, we have two girls (twins, they are currently still in the NICU, premature) but without him I have a two year old girl (her father is absent.) As of right now we don't live together, but he is still wanting to get married and move in together asap. But honestly, I am at home every day with my two year old, and I go up to see my twins in the nicu every day. I have to call medicaid and wic and social security I have a case worker for the twins and all kinds of other responsibilities, and I very rarely have a break, and the random night I do get away, I spend with him. But he has NO responsibility other than his part time job as a server. He sleeps in late goes to work then goes to a friends house and drinks or smokes or whatever he does. I mean, around twice a week he's out doing god knows what. Now here is my problem: I'm not sure if I am jealous of his absolute freedom and obvious lack of responsibility, or if I just want him to stop doing any of that so often and maybe sleep normal hours and only go out like twice a month. (I feel like that would be the responsible way for him to act with two newborns and a step daughter.) When we do get a place together after the girls come home, I don't want to be sitting at home watching three kids while he is out partying. But also as of right now it seriously irks me off to the point of not wanting to talk to him when he goes out, or when he sleeps in until one pm after having stayed up all night. I am not completely sure how to handle the situation, but I do want to know if my feelings (almost complete resentment) towards him are normal.