his kids are not responsible for his thought or actions, therefore you can not penalize his kids by not allowing them into yeshiva- nor should you let your children know, because then it will get around school and these poor kids will be mocked, ridiculed, and ostracized. and don’t say that doing so will cause him to seek help etc. because someone as messed up as to attempt murder or even entertain the thought has some real issues- and doesn’t think of others. but i would advise that you try and distance yourself from that person and confide in a well respected rav about this issue.
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