Nested sidebar behavior

I have a nested sidebar that goes 3 levels deep. I would like the interaction to slide left/right:

So in this example, if you click on "Jobs" in (1), (2) would then slide in. My question is, when (2) slides in, should its first item be active by default?

I tried that interaction, but the problem is, if the user is creating a job (which would mean they're filling out a form), if they inadvertently click "< Back", then the entire screen is going to get replaced by the Home page.

An alternative is - if the user clicks on "Jobs", this sidebar switches to (2), but nothing is defaulted here. "Create Job" will only bring up that page if they explicitly click on it.