I am sorry that you are under such strain op and feeling overwhelmed 💐
If it is only you atm op who is capable - when well - of looking after the puppy, then I am afraid to say that you might consider giving it back to the breeder as you are not in a good place to give it good care currently. It’s only been a week and you have many more weeks of broken nights to come. And the puppy is obviously the straw that has broken the camel’s back.
Please don’t feel guilty, believe me, I know what caring for a teen with ASD is like. It can drain you to the very core as you absorb their suffering and feel so distraught for them. It can be very debilitating. .
Op if you are at the point where you are having three-hour crying sessions at work, then you need help! Please please go to your gp. Get signed off sick. Get some meds on board and sign up for talking therapy.
I know that your dd loves the pup and it is doing her good and it will be hard to part with it now you have brought the dog home, but what your dd needs most of all right now is an emotionally healthy mum.
And if the dog has only been with you for a week then the sooner you get it back to the breeder, the better, before you miss those vital training windows and it becomes unmanageable and another strain on you.
Have a serious talk with your dd. Presumably if she is struggling herself atm, she won’t be capable of looking after the dog by herself while you recover? She may or may not understand you having to give the dog back but irrespective of that, you need to do the right thing. And you need to put yourself first atm. You can’t support others while you are so worn down yourself.
Good luck with everything. I hope you feel much stronger soon 💐
Edited: I have just read your update op about your dd doing a lot of the care. Are you getting up in the night? Is that the issue? Or is that having one more thing to feel responsible for is tipping you over the edge?