Moving on can be difficult, but it's a choice you have to make for your sake and that of your kid(s). I know it's hard when you're left behind by the one you love, but don't turn that hurt on your kids, don't try to fill them up with resentment and anger towards the spouse that left. Instead try to shield, love them and be there for them. It's a process and with time you will all heal, but let the healing happen, don't let yourself be stuck in the pain. Choose to move on, choose to be happy.