Leaving SO..

we have been together 4 years im pregnant with baby number 2 which is making it harder on me because my daughters 2 and he watches her at night while I work.. i get one day off a week and if i even so much as sit down for half hour he calls me lazy and critisizes what i do ... i constantly try to tell him i dony want our relationship anymore but he just ignores me.... how do i go about this.. he wont sit and have a conversation