Really need help!!

My fiancé has turned into a complete ass. He is always grumpy & complaining now. In front of family he treats me so good but when we are alone he just gets angry for nothing because he feels like all I want to do is sleep because I'm pregnant, which no I don't sleep because I have a two year old & a job.. Anyway, he gets mad because I don't want sex all the time now, & or he'll get mad because I pay my son so much attention and want to take my son everywhere, and he constantly says I'm not attracted to him anymore! I just don't even know what to say or do. Leaving is NOT an option.