Wherefore (hothen). This relatival adverb (cf. Act 14:26; Act 28:13) gathers up all that Paul has said.
I was not disobedient (ouk egenomēn apeithēs). Litotes again, “I did not become (second aorist middle indicative of ginomai) disobedient” (apeithēs, old word already in Luk 1:17).
Unto the heavenly vision (tēi ouraniōi optasiāi). A later form of opsis, from optazō, in lxx, and in N.T. (Luk 1:22; Luk 24:23; Act 26:19; 2Co 12:1). Only time that Paul uses it about seeing Christ on the Damascus road, but no reflection on the reality of the event.