I think it isnt selfish at all. In fact I think taking time to recuperate takes away the toll on the your family when you are feeling so overwhelmed from all the stress.

It's actually quite therapeutic to be alone sometime. In fact, I even made a ppst aboit it not so long ago. Yoy need to value time with yourself just as much as you balance time with your family

You have a great family. Good luck raising them i hope you gain inspiration in what you do!