Pregnant and financially dependant

Has anyone ever considered leaving their SO, but found it difficult due to the fact that they left their career behind as a SAHM?

I became a SAHM for my step sons (youngest was a baby when I started dating my husband). The only jobs I have kept since they were little were night and weekend jobs working around my husband's work schedule and daycare/preschool jobs where work and childcare was affordable. I left my education behind while caring for his kids, and had one of my own in the process. Now we're on our second child together, due in two months, and I don't know if I want this relationship to continue but I don't know where to turn. I don't want to leave my step sons behind, I'm financially unprepared, and my college education is lacking. My mother is dead, father is out of the picture, and I don't have any other family to turn to. Any advice from women who have been in this situation before?