I'm sorry for your dire troubles, FenwayFaithful. It is an awesome challenge to come to grips with ourselves when we decide we have had enough and we want to quit drinking and live our lives sans alcohol and happily productive and free.
When I finally quit, I had a plan to do a detox, and a rehab stay, and a program, and just keep doing it right to get away from my drinking. It took me three months, and I graduated from the rehab, and i've been sober since through any and all good and bad times now for many years.
I too drank away opportunities, and I was a disapointment while drinking... which really means i had good reason to stop, lol.
I think if you work with your parents the idea that you need to get free from alcohol NOW and NOT LATER, and that you have solid plans to do so and follow up with then returning to your studies eventually, you'll have them understanding your challenges with their own sense of insight into their beloved daughter.
You know they love you, and so, let them love you as you are now being challenged, and not just as if you've already failed them so much that there is no room for love and forgiveness. I'm sure they want you to be free from alcohol if alcohol is your ruination...
As for the boyfriend...
you don't need the trouble, you know?
do what is right, and then take another look at yourself, and do some more right, and another look as you progress, and I'm sure you'll see that your ex needs to be in your past and not in your future...
I hope you do have a heart to heart with your parents ASAP.