For I will declare
to front, i.e. stand boldly out opposite; by implication (causatively), to manifest; figuratively, to announce (always by word of mouth to one present); specifically, to expose, predict, explain, praise
perversity, i.e. (moral) evil -- fault, iniquity, mischeif, punishment (of iniquity), sin.
I will be sorry
be anxious -- be afraid (careful, sorry), sorrow, take thought.
for my sin
an offence (sometimes habitual sinfulness), and its penalty, occasion, sacrifice, or expiation; also (concretely) an offender