Regardless of how much effort you have put in, if the result is abysmal, then it is time to be honest with yourself. That the incredible amount of effort that you have contributed simply does not work. You need to get over this as soon as possible, suck it up and find out what can you do to have a great result. There is no point in hanging on to something that does not bear results for the sake of reminiscing lost time and energy spent. It will be more of a waste of those if you continue to do so. It is okay to admit that the actions you take were not the best as long as you are clear that it is only a failure if you give up then. Learn from the experience and sought out ways of how you can do better. Remember, efforts are efforts but results are results.