Double negatives exist in English, but their usage is considered grammatically improper. In Zekaiseivarsei, however, double negatives can properly be used for emphasis.
The sentence literally translates to "not I love you nothing" (or "I do not love you nothing"). In Zekaiseivarseivarsei, though, it means "I don't love you at all."
What if I mean to negate the negative? Edit
If you mean to negate the negative, simply use the NEG ya NEG construction.
dwi zi ya zi sha e sha ra (two not PARTICLE OF RELATION not one and one PARTICLE OF EQUALITY, English: two does not not equal one plus one.) This means that two equals not not one plus one, which is the same as equaling one plus one.