aww Corelly I could have written that myself. My DD is 14 months and this is our 2nd bout of night waking, once at 7.5months until 10.5 months thats when we started controlled crying, and her sleep went fantastic again, and again now for the last 6 weeks, the last 3 nights ending with me in horrible tears. I am so sorry I dont have much advice for you because we are working through this too but I just wanted to say I know how you feel and also I am in the same situation with DH working late, up early etc.
I think its because we have had a major disruption to our lives recently which has caused some behavioural problems but who knows what these little ones are going through.
If you need to talk please PM anytime and I hope someone/something can help you. Make sure you talk to someone about it dont feel like you have to do it on your own. I called parent line this moring and they gave me some great advice which we will be putting into action tonight.
again I hope it gets better and you get some sleep soon.
xoxoxoox