colloquial language - what does 言われなくちゃなんねェんだよ mean?

A manga character says this to someone who told him to やめろ:

なんで やめろまで言われなくちゃなんねェんだよ!!

Is that 言われなくてはならない and if it is, how can it be part of a question (with "nan de")? I don't really understand this sentence at all.

Answer

First, understand that やめろ is a really raw/strong/rude way to say "Stop (it) !" so I won't translate it to keep the strong meaning. (Other answers are missing this important fact. The speaker does not complain about being told to stop, but the way he is being told to stop.)

With your context, this sentence would mean: Why do you have to go this far by telling me やめろ. (ie: You could have been more gentle, a softer way to say this blabla....)

なんで sets the question.
やめろまで up to "やめろ"
言われなくちゃなんねェんだよ splited is like this
言われなくちゃ: 言われなくては
なんねェ:　ならない
んだよ: のです

いわれる: to be told
いわれなくてはならない => I have to be told

It's kind of Why do I have to be told things this far/rude as やめろ.