When I first read the premise my first thought was denial. No way! If that were the case there'd be no point in ever fighting anything! But if you keep going there's actually some really interesting conclusions here. Ender's Game makes this very clear.
You Must See Things As Your Enemy does.
You must be able to empathize with it. After I became a teenager this is a theme I began to see everywhere. It's a truth we are more willing to admit to than say...
Empathizing with evil may lead you down a dark path
This is equally true, maybe even moreso. In the same way that absolute power corrupts absolutely, Giving evil thoughts space in your mind will corrupt it. But in this case it isn't so black & white. There are levels of corruption, thus it's possible to not have any self awareness of how far you've fallen. You must find ways to...
Protect Yourself
This is key. Most of the time we set ourselves up for success without even noticing. But in those conflicts that make us anxious, it is imperative we have mechanisms that we consciously use to protect our sanity.
Avoid the conflict: If there is nothing that you will gain from fighting, just walk away.
Set limits: Before you engage your enemy, make the decisions about how far you will go. Go ahead and draw the lines before you are worried about crossing them. Setting limits is an important psychological asset in any conflict.
Have a silver bullet: Through blackmail or bribery, or the ultimate weapon. It may be time to reveal your hand and completely destroy your enemy before you become him.
Use a proxy: Lastly you can have someone else fight for you. Preferably it is a person that already has dirt on their hands. They are willing to help, and you can compensate them.