Best advice from above repeated: Just sing whatever you want to sing and you'll enjoy it more.

My two-pennyworth: one of great things about trad folk in general but ballads in particular is that you can, and in my view should, hack it around until it feels comfortable to you. The Child ballads are (in the main) full stories, so you can leave out sub-plots if you wish, or rewrite part of it so that the events are seen from a different character's viewpoint, or emphasise an aspect that appeals to you, or, or, or ... As a ballad singer, you are also a story teller so feel free to perform it straight if that suits you, or introduce some of the storyteller's techniques like changes of emphasis, pace and intonation. In short: you are free to enjoy yourself, so do so!

A free bonus with this - as long as you remember the story you are telling, forgetting the exact words is not that crucial!