Emotional Distress

Is anyone else having issues with their child's father? Maybe opting to separate before the baby's birth? I'm currently 33 weeks pregnant. 
It's my 4th child, his first. I know I can take care of myself and my children as I always have. 
He's been cheating and lies constantly. Same as every man. Promising to change, yet failing to act on those words. 
I just want to be ok by the time my son is born, and as things are now.... I'm falling apart. Loss of appetite, not sleeping much, and I'm trying to work extra shifts to compensate for my upcoming loss of income and to be distracted. 
I'm a little lost.