soon to have 4 KIDS UNDER 4YEARS

NEED helpful advice moms/dads:

I'm 28y, my fiancee is 23y. She already has a 3yr(turning 4 in a week) and 1yr(turning 2 in 2 months) from a relationship before, but we've been together for over a year now. In the 1st couple weeks of us seeing each other way back then, we got pregnant with our youngest (for now). That blessing just turned 6 months old and BAM! The condom breaks....so what is the positive outlook for this? Of course we are happy to have the chance to give life. What are the complications or precautions that we should take though?