funny you mention this Aliasalpha, I'm recently single myself.. only the ex is still living with me. :o

"One and only chance"? That's highly unlikely. You'll probably have plenty of other chances. I'm talking from experience, BTW.
If you want to be cheered up, there are quite a few choices. Light-hearted games are great for that - Lego Star Wars, Giants, even Abe games come to mind. Eat your favorite food, watch your favorite movie again, go to some public place and sit for a while watching people come and go, each with their own failures and victories, happiness and sorrow. You'll feel less alone that way too. ;-)
All in all, look at life differently, cherish every moment, and you'll be good to go - and be able to see new chances and opportunities for happiness as they come up. I'm convinced that happiness is less a state and more a way of seeing things. ;-)
I hope I helped... all the best to you!

If I need a cheer up or just to see other people than myself, I usually ride the bus the time of day, when the old folks go to their bingo :)
It can be really uplifting. Maybe only to see how young you still are compared to them - or because they are all so cheerful and excited as little kids on the way to a party, lol.

Go for the trinity - smokes, bourbon, and betting ponies. I'm not being sarcastic. This is how some of us get over breakups. Exercise and comedy helps, too. If it wasn't for the clean & press, I'd have gone on a killing rampage after one ex..... Try taking up lifting or yoga or something. Boosts serotonin and stuff.
P.S. There's always more chances. Give it some time. Happiness falls like rain. It doesn't flow like rivers. More fish in the sea. Etc... Good luck.

I'd suggest going to http://www.ocremix.org/.
When there, download the Sonic 2 remix album (and the other Sonic 2 remixes).
The majority of the songs are so upbeat, you'll be smiling in no time.

I like going out in town to buy a book or a cd. Helps a little.

Just go postal.

I'm cheered up and I wasn't even sad! Wow!

You'll need to find a girl as geeky as you are! It's rare, but I'm assured that they're out there.. Somewhere.
I've got my own "woman situation". There's this girl I had dated some years back, we broke up, and since then I haven't been able to get her out of my mind. Even when in other relationships, try as I might.
But I've got no chance. I'm 99% sure that she isn't interested in me, and she's engaged to boot. So what do I do? NFI.
My suggestion to you, like many others have said, keep occupied. Eat some comfort food. Put on some of your favourite music and sing loud enough to piss off the neighbours.
Apparently singing can actually be therapeutic.
You'll often find me stomping around my lounge room, singing to whatever metal band suits the situation. And you know? You feel better for those few minutes.
Chin up, and good luck.

Yay for retail therapy.

Hehe retail therapy has always been a favourite of mine too, its just a matter of having 2 important things, money and something interesting to buy, neither of which are abundant for me at the moment.
Thinking I might ignore saving for a holiday this pay and blow the lot on shiny things to amuse myself. Actually I might get the 4 DLCs for Fallout 3 that I've missed and play through that again. I've been thinking about playing it again and I do still have to play it as a regular person and as a bastard, the extra content could be just the shot in the arm that the game needs to freshen it up again. Hell why not just blow the lot on DLC? I'm still missing 2 addons for Tomb Raider Underworld and some stuff for a few other games. If I happen to have spare points I might even go REALLY stupid and actually spend money on a rubber chicken with a pulley in the middle for my xbox avatar
Oooh shit man, that's got to be weird. I hope it was one of the amiable "well we had fun but its not going to work, lets go back to being mates" sort and that you're not living with someone you're starting to hate. If so, get the fuck out ASAP and be sure to move anything you really value first so it can't br broken out of spite
Fun progress on my situation, I sent her the email yesterday and because it was such a depressing situation, I forwarded it to a few friends just because it explained the situation better than I was capable of at the moment. I mostly got replies that said "most beautiful / heartbreaking thing I've ever read" or "wow, I never knew you were so romantic / poetic" (how can people think I'm not poetic? What in the name of paris hilton's diseased rotting vagina are they thinking??) but her response was the least enthusiastic of them all.
It turns out I sent this most important and complicated message to her when she's got flu and is having real trouble concentrating. How fucked is my timing?
Whats worse is that I missed a few words that I should have added and have actually given her the impression that the cool/romantic trip I'd been planning for us to take for months before she was in this new relationship was a new development designed to break them up. All I needed to add was "for a few months" but it seems I wasn't thinking quite straight, to quote the late great Bill Hicks "who'da thunk it?"

Re: Retail Therapy
FO3 is always good. Life-destroying RPG-ness is what I'd go for, too. Did you play through NWN2? MotB is pretty much ridiculous (think son of Planescape). If you haven't played through NWN by some strange fluke, get Diamond. Pretty much netbookable, too.
That or JRPGs (Lost Odyssey, FTW).
How about gadgets?
You're somewhat academic, no? I wasn't really following any of the posts on the thread, but you're in Uni or Grad school, no? Have you thought about an ebook reader? Oh, God I love my 505. Sony gives you access to everything on googlebooks in ebook format.
A lot of people love Amazon's kindle (I've seen it , too, it's pretty nice, as well), too but the huge academic library courtesy of google tipped the scales for me for the sony.

There are a number of girls that would find that adorable, haha, for sure. Hard to find though, yes, hard to find...but if they were common, they wouldn't be so wonderful when you did find them.
Fallout 3 pack including all the DLC is coming later this year I believe, unless I'm behind..

If you want those addons, I hope you have the 360 version. :/