She was a witch who mastered Dark Magic, who had killed and who now everyone would fear. If escaping had not been confirmed as the only alternative to Azkaban, her place would still have been among the Children of Salazar. That's why she understood that she couldn't run away without speaking to the two Slytherins first. She had been wrong to deny herself, and she wouldn't recognize herself if she didn't go back and fix her mistake.