Rikka66 - too late for that, I can not stop anyone. Also, the whole group is shuffled and suffers from heavy confusion. The wizard being of high standing is exactly the problem, as I doubt common guards would dare stop him. Also, there is no time - the rogue simply went away while my wizard stayed to "control" another party member that used some drugs in body of my wizard´s wife and wants to go to the ball naked under the influence of drugs... I only have one concentration (Persuassion).
Vaalingrade - proving it is not that hard, problem is the attempt has been made and succeeded. Now it is just damage control. I do not see a way for the wizard to work together in the party with the rogue, even if there was no vengeance. Letting them kill my body is not something I would like to do, it is actually another thing to watch out for and protect her while she is in my body. What a nightmare.
ph0rk / Maxperson - I tried talking her out of it. Both player-player AND PC-PC. She does not care. I will have to cover my steps more carefully if I decide to kill her, I have an idea or two how.
Bradley Hindman - there is no out-of-game problem between us, that is just what she wants to do in-game. No out-of-game or meta reason. Just wants to do it. Love that sand castle approximation by the way.
Dire Bare - having her executed by law or by poison makes no difference to my PC, nor to the IRL implications. The game would still go on with her PC gone. Also, if I were to rebuild that (and I am not sure I could, such a thing would hardly be forgotten), my wizard would hardly just merrily go on questing with the rogue. No way of that happening.
******
Anyway, thank you all for your advice. Some of it was extremely helpful.
Conclusion - I explained here what happened and that I see it like I was cornered and have no choice, but most of you do not see it that way. So I have to very reluctantly assume the rest of the party would probably not see it my way either.
I have decided that I will not PC kill, because even though I can stay detached from the game and what happens there, I very much doubt she and some others in the party can do the same.
I will offer my wizard to the DM with the story that he swore revenge and left the party. There is no way they would work together after that, and this way I can avoid PC kill. The wizard will, I think, become the worst villain of the game. I can live (happily) knowing that. And I will roll a new character, probably a simple barbarian without a care in the world... or just find another party, a party with more decent players, where I would never have to solve such problems and react to such situations.
It is a shame, though. It was my first ever character. And I really liked him. Really.