If my actions send ripples throughout the world, then am I not responsible for those ripples? For those second-order and third-order effects of my actions?

You do realize that it is literally impossible to live without negatively impacting someone somewhere down the road, right? That is why you need to strike a balance, the balance between your benefit and other's losses.

Empathy doesn't imply that you have to put the feelings of others always in front of yours. To be empathetic means that you take the effects of your actions into account while deciding what to do. I don't see how that constitutes an existential crisis. Just don't do something if it will significantly hurt others.