Letting him cry it out

Today is Day 3. For the past 2 nights we've been letting Nathan cry it out. And while there's the minor victory of Nathan sleeping IN his crib - we're all exhausted. Friday night he cried from 1:30am - 3:30am when he finally went to sleep after hysterics and Jeff and I sat downstairs and watched a poker tournament on television. Which, by the way, why is it okay to use math in poker, but not to count cards? I'm just wondering. Last night Nathan cried from 10:45pm - 3am. We watched Star Wars on television about 1 and 1/2 times, and alternated between napping and miserably feeling like the worst parents in the world. We were using the Ferber method to get him to sleep but everytime we went up Nathan would get more and more hysterical that we were once again leaving him. So we started stretching the time out till about every 30 minutes. Jeff isn't sure if last night Nathan fell asleep on his own, or he helped since when he went up he tried comforting Nathan by rubbing his cheek and Nathan passed right out, exhausted. Oh, and was then WIDE AWAKE by 6am te next morning. I just put him down for a nap around 9am and he screamed again till about 9:35am. Where he finds the energy to continue his tantrums I have no idea because Jeff and I are a wreck. Jeff has to work tomorrow so we're planning on turning off the monitor and having him sleep downstairs. There's no way he'll be able to function if he's only got a second night of 3 hours of sleep at work, and at least I can nap the next day when Nathan naps... I've read from friends that this can take anywhere from 3 days to a week and we're really, really hoping it will be more like 3 days because this is worse than when he was a newborn. Maybe it's because he's started calling for us, and we can hear repeated words like "da da" and "ma ma" from upstairs and that makes us feel like ogres for ignoring him. I keep telling Jeff we're doing this for Nathan, that him being able to sleep on his own in his crib is good for him, but it feels AWFUL right now. Really, really awful.