About six months of bitterness and depression that prevented me from doing anything productive whatsoever.
I regret every moment of it. I did ABSOLUTELY nothing. I stopped weightlifting, I stopped doing anything with my band, and I stopped going out. I feel like I lost those six months of my life, and I understand now that it was completely unnecessary. If you're going through a bad breakup, do something productive to take your mind off it. Weightlifting/exercising is a fucking unbelievably effective means of dealing with stress; that's just science, but on the other hand, you'll be a lot more fit and you'll think "Damn, I look fucking good." It gives you a reason to feel good about yourself, and that's going to feel like a godsend during a time when you can't help but feel like shit.
The other big resolution you need to make is to see as much of your friends as you possibly can. You do NOT want to be alone with your thoughts during a period like this. Like the TC said, taking up a hobby will really help, since that'll keep your mind occupied as well. Still, it's much more important to just be around people you know. Go out drinking/clubbing/partying with your friends, as long as you aren't drinking yourself stupid to deal with your depression.
I don't know if I can really recommend drinking. The last time I went through a breakup (not nearly so bad as the one in question), I went and got myself a bottle of vodka, and on nights where I felt like I needed it, I'd have a shot or two, never any more. I'd drink just enough to loosen up and take the edge off, both because I can control my drinking and because I don't really enjoy being wasted out of my fucking mind. It's fine to drink that much once every blue moon if you're at a party or whatever, but being that drunk when you're in a shitty mood just doesn't feel good, and that's just a quick way to develop problems that will plague you into your later years. Again, this one really depends on how you handle alcohol. I've never been a heavy drinker and I've hardly been drinking at all over the past couple years, but I've always been the type to just have a shot at the end of the day, to loosen up or unwind on days where I feel like I could use it. I find it really lets go of the tension, but I just never want to drink enough to completely lose myself. Like, what I'm trying to say here is that it's alright to drink in small, SMALL quantities like this if you feel you can control it, but I leave that up to your discretion. if you don't trust yourself with it, don't do it just because some assclown on TYM said he's done it. In either case, if you ARE going to drink, you'd might as well get some Pinot Noir, at least that shit's good for you.
Other than that, the only other suggestion I can give you is, well, sleep around if need be. Don't let this define your life and don't let it become a compulsion, but if you think having a few hookups will uh, release some tension, go for it. Honestly, that's basically all I do at this point, whenever I feel I need it. I have a few FWB, some of them on-and-off, and I hit them up wherever necessary. I'm done with relationships indefinitely, partly because they've been nothing but stress for me (I've ended the overwhelming majority of them, for the record, so abandonment is the least of my concerns). More than that, I just don't miss it. Life is so much simpler this way, and I'm really enjoying it. I don't feel any kind of longing to be in a relationship right now, and it gives me so much more time to focus on my own life and what I'm doing with it. I have time to weightlift, I have time to write and record music, I have time to read, I have time to be a fucking nerd and play MK9 into the early hours of the morning. Like I said, I'm off relationships indefinitely. Until my outlook changes or I come across someone who makes me want to give it another shot, I'm not dating anymore, and I'm happy this way.
/rant, but if this is in any way helpful to anyone who's going through a bad breakup, I'm glad to be of service.