I think the hardest lessons to learn in life are the ones that leave the biggest impact on us. Being kind, caring and compassionate are wonderful qualities to have in life. However, when it comes to alcoholics/addicts we need to possess those qualities from a distance.
Your friend gave you a gift, an important life lesson that can benefit you moving forward in life.
And always always always trust your gut instinct!!! You mentioned that her mom and dad begged and begged you to shoulder this situation and that you caved. Meaning you knew somewhere deep down that the situation was not a good idea and would probably leave you regretting it.