I am so sorry to hear that! Your decision really was for the best, though. Our pets deserve to be treated right, and if we see that we can't afford to give them the life they deserve... then the wisest choice would be to give them away. At least you didn't leave her on the street as many other people would do. And I'm sure she will find happiness wherever she is.
In any case, I know it must have been an extremely difficult decision. I have been in a similar situation and I know how painful it is. Pets truly are wonderful companions and they make our lives so much better. I hope she's in good hands now and that the people she's with will occasionally contact you to tell you how she's doing. Best of luck and fingers crossed that you'll feel better about the whole situation soon