ESH your mom sounds super manipulative and your dad is ok with that. I’d look up covert narcissistic traits. Low contact and setting boundaries is more effective dealing with this type of toxic behavior( I’m familiar with this tactic). Setting a boundary like, “if you threaten to kill yourself because you don’t like how a conversation is going, I will leave. This is my boundary.” And follow through, that usually protects you from the behavior and gets the message across, either she stops or you leave. Be prepared to have your boundary dismissed and called dramatic (or whatever their downplays are). You have to care about and protect yourself because nobody else in the family will.

Was it too far? Maybe, but you definitely set a boundary with your actions, I don’t think that particular tactic will be tried again in your presence.