Policy specifically says to use Breaks in this case: "Breaks should be
used [...] when the breaking package exposes a bug in or interacts
badly with particular versions of the broken package." (same section as
above)
according to this, I can use "Breaks" in situation, where my package is broken with older version of other package and I can "Breaks" older version of that not compatible (interacts badly) package.
Am I reading it correctly?
Because that means "Breaks" works both way. If A breaks B: A doesn't work correctly with B or B doesn't work correctly with A.