How do I go back to work as the parent I am now?

You left one person and returned another. Your team, your manager, your partner — they expect the person who walked out the door. They have not lived what you lived. This is not their fault. But it is your problem to fix, and no one will fix it for you. The easy path is to say nothing. Slide back into the old shape. Smile through the first meeting, take the same travel, answer the same late messages, and tell yourself you will adjust later, quietly, on your own. This never works. Resentment does not stay quiet. It leaks into your work and your home both. The honest path is harder and shorter: say the terms out loud, to the actual people who share the work with you, before the first crisis forces the conversation anyway. This is not selfish. A team that knows your real terms can plan around them. A team guessing at your limits cannot.