Leave her and go find Rachael

While it pains you, it won’t be much help for both of you to get caught, and your uncle needs her alive and well to secure his rule. Of course there is also Rachael, who knows just who and how many are after you. Finding her will give you the best source of intelligence and a chance to come back and save your sister. Without giving it a second thought, you wish your sister goodbye and slip out the window. The muddy road helps with your fall allowing you to quickly take up following Rachael's trail.

You race across the muddy road in pursuit of the wench you two just fucked.

Her feet left tracks in the mud, which leads to an abandoned farm house about three hundred yards past the gates of the town.