Is assisted martyrdom - desirable or is it murder?

Maharam M’Rothenberg(2:59): Question: During the massacre of the Jews in Koplinsh a man’s wife and 4 sons begged him to kill them to save them from falling into the hands of the mob. He did so and then also tried to kill himself but was prevented by others. He wants to know whether he needs to atone for killing his family? Answer: I don’t have a clear legal answer to this question. On the one hand, the gemora clearly indicates that it is permitted to take one’s own life to sanctify G‑d’s name… but to kill others it is not clear what the halachic basis is to permit such a thing… Nevertheless, it is obvious that it is permitted since we have heard about many great sages who martyred their sons and daughters [to save them from the Crusaders]. … Whoever would require atonement in these cases is slandering our pious ancestors. Since his motivation was love of his Creator and those he killed were his beloved family and they begged him to do it, …there is no basis to require atonement.

Daas Zekenim of Baalei Tosfos(Bereishis 9:4): And surely your blood of your lives will I require… - This is a prohibition against committing suicide. Bereishis Rabbah asks, “You might mistakenly think that this prohibition applies to cases such as Chananiya, Mishael and Azariah – therefore it says “ach” (and surely). That means that you might think that even in this case where people are dying to glorify G‑d’s name that one is not allowed to bring about one’s death - even if he is afraid he cannot withstand the pressure to violate the Torah. Therefore the Torah says ‘ach’ to teach that in times of pressure to violate the Torah - that it is permitted to commit suicide. Similarly concerning Shaul who committed suicide to avoid being tortured – an exception is made to allow suicide in such cases where a person doesn’t think he can withstand the torture. This analysis is used to justify killing children during times of religious persecution to make sure they are not converted...

Daas Zekenim of Baalei Tosfos (Bereishis 9:4): And surely your blood of your lives will I require However there are other authorities who prohibit suicide and killing. They say you might mistakenly think that martyrdom is only permitted in the case of Chananel Mishael and Azariah because they were already sentenced to death – therefore the verse says ‘ach’ that one can refuse compliance with demands to violate halacha and thus bring about death - even if not already sentenced to death. But in any event one can never commit suicide. One can only bring about one’s death at the hands of others for not complying with demands to violate halacha. You might mistakenly think that an exception is made in a case such as Shaul who committed suicide to avoid severe torture. Therefore the Torah says ‘ach’ to say that there is absolute no situation where suicide is permitted and in fact the Sages disapproved Shaul’s suicide. There was an incident where a rabbi killed many children during the Crusades because he was afraid that they would be forced to convert. There was another rabbi with him who was extremely angry at him for doing so and called him a murderer but the first rabbi ignored him. The second rabbi told him, that if his view not to kill the children were correct then the first rabbi would die a horrible death. And thus it was. The first rabbi was captured by the Crusaders and they flayed his skin and placed sand between his skin and his flesh. In addition the decree to convert was nullified and if the first rabbi hadn’t killed the children they would not have been pressured to convert.