Don’t get caught up in beating yourself up and feeling ashamed for going back, it will just sap your strength and distract you from getting you and the kids away from him. You believed in his better nature and he didn’t deliver - that’s on him, not you. At least now you know for sure he won’t and can’t change, and you can use this knowledge to fuel your determination to leave.
He’ll be watching more carefully now, but there will still be opportunities - when he goes out, when you take the kids to school. Be prepared. Gather the basics you need and have them to hand. When you can leave, you must report him to police, including the rapes. They will likely arrest him, giving you more time to go back to the property and gather more things.
PP’s suggestion of speaking to the school safeguarding lead is good. You can shelter at school while the police are called.
It’s a hard step to take, but posters here will help you with a plan. Once the hard step is taken, after the initial period, things will get a million times better for you and your lovely children.
Just imagine what life will be like for you and them just one year after leaving - close your eyes and imagine what that feels like - he isn’t around, there’s no walking on eggshells, no fear for your or the kids, waking up each morning knowing how you feel won’t suddenly change for the worse based on his whims. The freedom. Feels so good, doesn’t it? That’s what’s waiting for you and the kids once you leave.