Demonform: Semantics of "Lifelose" and "Damage"

So I want to do a Demonform build and it is rather frustrating. Not because of the bugs, but because the wording in PoE 2 is very unclear.
In the description of Demonform it speaks of "Lifelose" per second, so "Heartstopper" (Damage over time is reduced by 50%) should work and cut the damage in half right?
Now, some people have told me that "Lifelose" is not counted as "damage" therefor Heartstopper doesn't work. Is that correct?

On a different note, the recoup passive skills also don't work as they only care about "Hits" which are one time damage effects; so no "damage over time".
What I ask myself now is, if it would trigger with the "Pyromantic Pact explosion"?

Ty everybody