One honest suggestion I'd like to offer you is to consider that the studies that support the "letting babies cry is harmful" side of this argument may be just as questionable as any other quasi-scientific advice new parents get. The "La Leche League", which you linked to, is definitely guided by some dogmatic principles that I think are a little on the nutty side and I don't consider them very trustworthy. It's been a long time since I researched this so I don't have all the evidence handy, but I recall that their favorite study to cite about the harm of sleep training is the canadian "Early Years Study", and if you look at the source of this study, it does not mention sleep training at all. In fact, the only references to babies crying in the entire study is a hypothetical situation where the baby is stressed because the mother is letting it cry and the father is yelling at the mother in front of the baby. This is an example of La Leche using a study to push an idea that the study absolutely does not support. Just be aware. Read the references, decide for yourself, and take everyone's input (including mine) with a grain of salt.
Edit: and don't forget to give yourself a break, because all you need is love. :P Sorry, couldn't resist.