、。
Don't be sad — I didn't mean to hurt you.
Literal
Feel-down-[negative-imperative-なよ], you [object-を] hurt [intention-つもり] was-not [explanatory-んだ].
~なよ softens the plain negative imperative ~な with a friendly よ, yielding 'don't [X], okay?' 傷つける is transitive 'to hurt / wound [someone].' つもり marks intention — 傷つけるつもり = 'intention to hurt,' ~じゃなかった negates it. The んだ ending frames the second clause as an explanation/reason.