Viki, I don’t believe that she “chose to hate.” On the contrary. Her healing journey required the young woman’s mom to reach out to you since you did not reach out to her first. In her view it was a wrongful death caused by a drunk driver. She will probably never find the same meaning in her daughter’s death that you found in your son’s death, but that’s not to say that she lives her life in anger and hate. She just needed to express her loss to the only person she could. Since she cannot talk to the person responsible, you were just the next person in line. I’m sorry it was hard to take, but she was justified in doing that. (You do see that, I hope.)
It’s impossible to see clearly through grief, though, and impossible to mete justice through it. I am sorry for both of your losses. It sounds like you handled it with some grace, except for your interpretation of the experience. No judgment. I see it in myself, too… grief is the most self-centered state I’ve ever experienced.