domus: Cicero's family were, however, urging him to join the Pompeians. Cf. Att. 9.6.4 praesertim cum ii ipsi, quorum ego causa timidius me fortunae committebam, uxor filia Cicerones pueri me illud290 sequi mallent, hoc turpe et me indignum putarent; nam Quintus quidem frater, quicquid mihi placeret, id rectum se putare aiebat, id animo aequissimo sequebatur.
gener tuus P. Cornelius Dolabella, who was a pronounced Caesarian.
illud cogita: see note on nihil, 1.
offensae: on offensa, Meyer (De Ciceronis in epistolis ad Atticum sermone, 17) says: used only in conversation. Cicero himself does not use the word even in his letters, employing offensio in its stead. The more colloquial writers of a later period, however (e.g. Plin., Suet., and Petron.), use it frequently.
optimatem [gap in text] optimum: the singular form optimatem, which is very rare in Latin, is used here for the sake of the pun with optimum. Don't be so good a nobleman as to shut your eyes to what is noble.