(Still here? I could almost think you like learning about the mechanics of writing… or at least like seeing the sorts of mistakes other people make because that makes you feel better about your own writing skills.)
Use a comma to separate a direct address (any direct address — it doesn’t have to be a proper name) from the rest of the sentence. If the direct address isn’t the first word, you need a comma before it and one after it.
Honestly, darling, why are you fighting against a cause that created you?