That's odd.... maybe it's a misprint or a misinterpretation of something. How could Dante be responsible for his brother's personal choices, or his mothers death if he was only 11-10 years old at the time she died?
It'd be a bit unfair to suggest Eva's sacrificing herself to save Dante was Dante's fault, or that Vergil was corrupted because Dante stopped him from obtaining the power he wanted.
There's hardly any info on the twin's past, but the manga suggests Eva told Dante to hide while demons attacked, and it suggests Vergil put up a fight instead but in no way does it suggest Dante caused either of these things. I don't know about Eva, but doesn't Dante even try to talk Vergil out of his power hunting a few times? He's really not responsible for either, from what I can see.