Your notion that she in any way "caused" someone to be abusive is the biggest red flag in this entire situation. You should be far more concerned about your own alarming victim-blaming mindset than what she did "that caused him to be so abusive". The fact that you're more willing to use this as a reason to point fingers at the victim than to express love, care or compassion says quite a bit about your own empathy levels.

Abusive people are usually so because they've come from from troubled upbringings and unhealthy / toxic environments, not because their partner got it out of them in some way.

Being as it's pretty common for victims (especially women) to blame themselves for abusive male partners, doesn't mean she actually has a "valid reason" for his abuse to salve your consciousness (like that's somehow more important than expressing compassion for the fact that she's been abused!) It likely means she's so entrenched in blaming herself at this point, she might not even have any reason, she just feels like she "just is" at fault.

You should be ashamed.