Boundaries and Buddhism
The Pali Canon position (e.g. Sedaka Sutta) is that :


  [Correctly] Looking after oneself, one [implicitly] looks after others.
  [Correctly] Looking after others, one [implicitly] looks after oneself.


The Mahayana position is unquestionably that of service without boundaries.

That said, both the Buddha of Pali Canon and the contemporary Mahayana teachers insist that taking care of oneself is a prerequisite to being able to take care of others. To use a modern analogy, first put the oxygen mask on oneself, and then help the children.