Immigrant Families- Was Trump’s executive order the ‘best case scenario’?

I know there are a few posts about this, but hopefully my question is different enough to be seen as worthy of another post... sorry in advance if you don’t agree.

As we all know, today President Trump signed an Executive Order to end separation of families who cross the border illegally. He did this after making many statements saying he thinks that congress should ask on the laws if they don’t want them enforced as they are written.

His administration was criticized for taking a zero tolerance approach to these laws. The acting director of ICE also addressed congress with these comments:

The president only has the ability to make executive orders, which are decidedly more temporary and less powerful then actual law reform. I am wondering if you all think an executive order was the best possible outcome, or if you would have preferred congress take the lead in making changes to their laws as they are written... OR, do you have a completely different take?

I am not really trying to debate the separation of illegal immigrant families, but rather who’s responsibility is it really to fix it. My feeling is that congress took the position of being outraged over a law they established, and that seems backwards to me.

Bonus Questions I feel are relevant:

Is a zero tolerance policy on laws acceptable? Only on some laws but not others? Are there certain crimes that should be ignored by law enforcement, or in this case ICE?... and if so, is grey area in law a good thing?