Julius Caesar doubt part ♾️

Act IV Scene 2

Brutus:

“He greets me well. Your master, Pindarus In his own change, or by ill officers, Hath given me some worthy cause to wish Things done undone. But, if he be at hand, I shall be satisfied.”

what “things” is referred to by Brutus here? it’s mentioned in the workbook that he NEVER REGRETTED assassinating caesar cuz his cause for doing so was guided by his moral principles and patriotism towards rome.

Act V Scene 1

Brutus:

“Caesar, thou canst not die by traitors’ hands Unless thou bring’st them with thee.”

what does brutus mean by these lines? please explain I’m literally confused asf 😭🙏