So okay. That one is easy. Just forgive your little shit of sister. Honestly. Just don't have any hard feeling on her and get rid of that feeling of wanting to take revenge...Let it go. Just kill her in a natural looking way. And if it doesn't look to be going well, hire murderers to ambush her in a unguarded moment, when out. Surely a dangerous measure, as this leaves wittnesses/blackmailers, but it is still better, then keeping your murderer in strikiung distance of your throat. You have your memories, so it should be possible. But firstly, as the veeeery first thing to do, ...GET RID OF THAT DAMN SMIRK YOU FOOL! ACT LIKE YOUR FORMER SELF!!! Then hire you own maids and defuse your old ones. Blackmail them into answering to you and just you. If you get rid of them, that little bitch will replace them with others. Its enough if they stay silent until she is gone.