。
She accused me of being insincere.
Literal
She [topic-は] me [object-を] insincere [as-だと] accused.
The frame Xを Yだと非難する ('accuse X of being Y') uses を for the person being accused, the copula だ, and the quotative と to package Y as the content of the accusation. 不誠実 ('insincere, dishonest') uses the Sino-Japanese negative prefix 不~ on 誠実 ('sincerity, honesty'). Compare with the parallel prefix 無~ as in 無責任 ('irresponsible'): 不~ tends to attach to qualities one ought to have but lacks, 無~ to attributes one simply doesn't possess. 非難する ('to censure, condemn') is a fairly weighty verb — heavier than 責める ('to blame').