Hey Rich,
I have a similar story to yours, minus being in a frat. I would suggest sticking to 90 days sober, and getting whatever support you need, whether it's here, AA, SMART, a therapist, or a combination. I'm quickly approaching the end of my 90 days and if you take a portion of that time to be self reflective on why you drank, what it's done to your life so far, it'll be easier to start over and become happy with yourself again. I too felt very sad and alone while I was drinking a lot (we're the same age by the way), and trust me when you're sober it's not easy to deal with the suppressed feelings, but with some positive reinforcement you start to truly live again.