First of all, you can do this. Being a single parent is much better than being in a one-sided marriage. (I know from experience.)
Secondly, children are extremely resilient. Yes, they're going to be upset, and there will be rough spots, but they will adapt. The most important thing is to constantly remind them that mommy and daddy both love them very much, and the divorce is not their fault.
My girls were 6 and 3 when their dad & I separated. They were understandably crushed, but (3.5 years later) they're doing great. I'm amazed at how much they've weathered. Since my divorce I've remarried (adding a stepdad and 4 step-siblings to our family), we've moved to a new town (adding new schools, a new house & new friends to the mix) and they haven't heard from their dad in almost 3 years. And yet they're happy, well-adjusted kids.
You can do this. Your kids can do this. You go girl!