A. - I am a co-sleeping, attachment parenting, extended nursing Mom and after doing this with 3 kids (including the adopted one, though I was not able to nurse him) - I feel I can say with conviction that nothing - NOTHING - is more important than SLEEP. YOUR sleep! Not theirs - they'll get naps while you are at work. : )
We cannot take care of our babies if we do not take care of ourselves.
So if the only way you can get sleep is to do a few nights of CIO, it will not be the end of the world. I didn't do it often, but by son 3, yes there were times I let him cry. He's 2 now and he's fine.
It's my understanding that most kids settle down after 20 minutes and 3 nights. Do what works for YOU so you can function and GOOD LUCK!
ETA: If your baby cries for more than 20 minutes, I understand you do need to comfort him. I don't think most "CIO" parents mean "we locked him in his room and ignored him all night until he gave up on us".
I weaned my baby at ~ 2 yo. My husband started sleeping with him at first, so he didn't go from full-on all night comfort nursing to nothing. And comfort nursing is only a problem in that it can lead to one exhaused Momma. Whatever you do, remember a loved, fed, and warm, heathy and happy baby is the goal. The rest is gravy. I know what it's like to be on the verge due to lack of sleep.
You need to stay employed, you want to be the best Mom; you have to find a compromise and that cannot mean you're seeing caffeine fairy lights and falling alseep on your drive home. I've been there ~ best of luck to you.