Mine were 4, 2 & 9months old when their dad left. They are now 17, 14 & 13.
I've always worked full time, no support from my family parents both died before DCs were born, XPs parents lived 70 miles away, but have been generally lovely. I had excellent affordable childcare while they were at primary school & their primary teachers universally adored them,
A few shaky bits along the way..their dad is now a violent alcoholic & we moved 500+ miles away from him two years ago, so I could take a promotion at work. There have been problems with 2/3rds of them regarding 2ndry school. DD has more or less dropped out of her 2nd year of A levels, which, to be honest is disappointing...but she is beautiful, assured, takes no shit & has a lovely bf & a part time job. DS1 has lots of problems at he moment, but I don't attribute those to a mono-parent household. At his best he is kind, hilariously funny & very, very talented. DS2 is just lovely in all ways. He is a joy. Tries SO hard at everything, never gives up.
It's tough. Although I earn twice as much as when XP left (which is just as well as he contributes sod-all) there is never enough money. We've never had a family holiday, the DCs don't have after school activities, they have always had packed lunches etc...
As they've got bigger, it's got easier...& more complicated. But I guess that happens. :). You can absolutely do this & your DCs won't be any the worse for it.