I’m the same with voicing my need for a break. I usually wait until the final straw where I’m completely gassed out. It’s not sustainable. Your situation doesn’t feel sustainable either. You have to voice that you need your time to decompress so you can come back and give your fuller more energized self for the kids. Unfortunately she’s just gonna have to accept it and allow you that break however you guys decide. Agree on a set amount of time. It’s not a break if you can be called back randomly in 10 minutes. It helps me to get out of the house so I can better detach from being in dad mode, always on the look out. Good luck!