Living with a manchild

Okay I hate to complain about my fiancé but I'm just tired of him being so lazy. We both work in law enforcement at the same department and for a long time he never did any Overtime because he burnt himself out the last time I was pregnant trying to keep us comfortable while I was on light duty and couldn't do any OT and he never helped clean the house he spends every waking moment on his Xbox One and never gets up to clean a dish or help get the kids ready to go or even take out the trash then in about June he injured his knee and was off for about 8-10 weeks waiting for surgery then recovering from it, the surgery all they did was go in and scope it and scrape away stuff that was not supposed to be there and I didn't ask him to help with any chores or even bug him about always being on the game but he healed very fast and was released from Physical therapy after about 2 weeks and even was back to running and not feeling any pain so I started nicely asking him to help clean the house and pick up after himself while I was at work or while he was up all night keeping his night shift schedule that way he wouldn't be to exhausted when he went back to work. He never helped I asked him to do the trash and even just clean up after himself he won't get up to do anything so I became frustrated because at this point I had been working everyday 12-18 hour shifts and I never had a day off and then I would come home and clean the house do the laundry, give our children baths and cook and thaw food, and get kids ready for school and daycare and help the boys with homework all while he sat on his butt playing video games then going to sleep and nothing more so I snapped and began yelling at him and somehow he always made it seem like I do t want him and would make comments like well then why are you with me. Honestly I love him he doesn't abuse me he's good to our boys he works and doesn't cheer on me and shows me affection but he sits around the house all day like he is a guest and has no obligation to help with taking care of the children or chores and now he has been back to work so he uses that as an excuse why he can't help he only works 1 or 2 extra days a week so he is still not working like I was and oh I am now 23weeks pregnant with our twins and they are draining my body I can barely get myself ready in the morning and I still do all the house work and care for our children the exact way I have been since before I got pregnant. I am back to light duty which is only 8-4 5 days a week so I should have more energy you would think but because of how bad these babies are draining me I am physically exhausted. I just don't see the point in us living in the same house if I am the only one maintaining any of it and it's so frustrating because it doesn't matter how I approach him about it he gets defensive and none of it ever makes any sense at all