Since you already did it, it's too late to use an offline computer. Now all you have to do is import the private key in your Bitcoin Cash wallet. I assume you have one already, if not, you'll have to download one first.
Since you've been exporting private keys and (worse!) using your recovery phrase on an online computer, you should now consider your Ledger Nano-S wallet compromised! I'm not familiar with the device, but I would recommend to first safe your coins and then restart everything with a new recovery phrase.
But, since you ignored my previous security precautions, there are several ways to mess up here! You have to be careful, paranoid and think about what you're doing before doing it to keep your coins safe.

Enough warnings, I don't want to be responsible for helping someone who ignores security warnings, that's just waiting for a disaster.