my fiancé has turned into such a jerk !

My fiancé, since working, hasn't been spending any time at all with our 2 kids. Work/sleep repeat. Which I'm okay with, I know he needs rest. But I'm also upto my knees with our kids/house each and every day with no help. He gets 1 day/night off and that's every Saturday, so I suggested he spend his days off with our kids, some quality time & that way I get a 'day off' too and have some me time. Well that discussion ends in arguements, anger & tears and is always left undiscussed! He wants to spend his night off drinking & partying with his mates cos he 'deserves it more' which leaves me home alone again with the kids. He says this is my job, it's what mothers are supposed to do & I shouldn't complain, but every Mumma needs deserves some me time, he just literally does not see anyone else's perspective but his own, and he is ALWAYS right. He says if I get a day off that's me not spending time with the kids which is what I complain about him not doing, but the difference is I parent them 24/7 7 days a week with no help whatsoever from him and he spends no time with them at all -,- I don't know what to do, how to feel id rather be a single mum then put up with his added stress! N doesn't matter which way I try to address how I feel he just doesn't see it any other way only his own :( it's killing me I have to argue about my fiancé spending quality time with our kids rather than alcohol and partying. I'm looking for ideas, opinions, encouragement anything. I'm just lost.