I verily thought with myself (egō men oun edoxa emautōi). Personal construction instead of the impersonal, a touch of the literary style. Paul’s “egoism” is deceived as so often happens.
I ought (dein). Infinitive the usual construction with dokeō. Necessity and a sense of duty drove Paul on even in this great sin (See note on Act 23:1), a common failing with persecutors.
Contrary (enantia). Old word (adjective), over against, opposite (Act 27:4), then hostile to as here.