Of course, it's a moment that clearly still haunts him. It's interesting how two of the most important moments of Guts' life are defined by rape. When Gambino sold him off and the Eclipse. Thankfully for Farnese Guts is far from helpless right now.
Also, I agree with Farnese about the beauty in Guts' struggle. He's fighting to keep his humanity and for his lover. It's not JUST revenge, though that's obviously a big part of it, he's also not running and hiding. Basically he's just a strong character and I don't mean just physically.