Relationship advice please

I am at my wits end. I love my fiancé, we’re expecting our second child together. But I just can’t stand how he lives. I work outside of the home and he’s a stay at home dad. Which I’m okay with. For a while he was keeping up with the chores and he takes great care of our son. But for the past few months he just...stopped. He’s never home (he takes our son where ever he is going) he doesn’t do the laundry or the dishes. He doesn’t clean up. He won’t cook dinner (my son gets fast food or microwaveable meals, yikes) He doesn’t even let the dog out of the cage and take her outside. I have to beg him to stay home and clean. He tells me he will and then I come home and it’s still not done. Even if he HAS stayed home all day. It’s to the point on my days off I do everything. The 2 weeks worth of laundry, the months worth of dishes. I also am the main one who gets my son up, fed and ready and his bag packed for the day unless I work before he’s awake. I don’t mind splitting the chores in half. I don’t mind having being the main one with my son when I’m home. But it is exhausting working 6 days a week 50-60 hours, while 7 months pregnant and have to come home and feel like I do EVERYTHING while he does nothing but play on his game. I’ve tried leaving. I simply cannot manage to handle him with another woman. It breaks my heart. I’ve also tried talking. Explaining to him that it’s hard to keep up with these things while he gets to go out and has fun with his friends or plays his game. He says all I’m doing is trying to fight and to just not talk to him. What do I do? How can I make him understand I can’t keep this up?