I'm not quite qualified to play Miss Lonelyhearts, but I'll take a shot anyway.
Getting your heart broken doesn't just suck, it sucks donkey balls. Even more so if it involves someone you have to see regularly, such as a co-worker, a friend of a friend, a fellow student, etc. Believe me, I know.
Unfortunately (and this is probably not what you wanted to hear), there's no magic cure for a broken heart. You need to get over it somehow, but it's usually not easy anyway, let alone if you still (have to) see that person often. It may help to try and adopt a more casual approach to love. It may help to drink IF (AND PROBABLY ONLY IF) you have the discipline to not become a problem drinker (in fact, going into a bar and pouring your heart out might even make you some new friends). It may help to focus on a hobby (which could be whatever tickles your fancy). It may help to start looking at other women with or without actively pursuing them.
In the end, the best I can say is that it will get better. Right now it may seem as if your world is ending, but over time you will start feeling less miserable, start feeling good (or at least neutral) more often than bad, etc. But still, you do need to get over it and that usually takes time (and probably lots of it). If you have no outlet (e.g. a hobby), you're just going to have to hang in there and ride it out. It may suck for a while, but believe you me it will get better eventually.
Considering that you also have a working relationship with this woman, the best I can do is to tell you to just act like nothing happened. Say hello when you meet her, but try not to care too much if she doesn't say it back. Don't bother her if it isn't necessary. If she is avoiding you, let her. After all, you both have to deal with what happened and it's probably not easy for her either. Just try to act normally. Again: over time, things will get better.
Best of luck!