Yes, it is harder than a new baby. Because that's exactly what you have, at 12 weeks, is a new baby... only it's of a different species... so all the baby issues don't come even remotely natural to you. Yes, you have taken on a huge job. But try not to let it wear you down. The rewards down the road can be WELL worth it.
The biggest mistake I have seen (and I've seen it many times) starts out with a situation like yours: you didn't want the dog to begin with, but now you have it and all the responsibility is falling to you. If you stand back and wait for all those family members who begged for the pup to step up and take care of it, all you'll end up with is a bigger problem. Because sooner than you think you'll have a grown dog that hasn't been properly trained. As hard as it will be, swallow your anger and remind yourself that the poor little pup that you have now adopted into your family had no choice in the matter, and is just a babe! He desperately needs someone to take charge of his life and teach him what he needs to know to be a wonderful addition to your family in the long run.
I strongly recommend that you research the best ways to go about this. I know you have a lot going on... and you are resentful that you now have all this work and responsibility that not only did you not want, you lobbied against. But you can do this to your benefit! You can crate train your pup, yes. And I highly recommend it, but at 12 weeks or so, your pup is a baby and cannot hold it longer than a couple of hours. And if his crate is too large, then he won't hesitate to go in it at all. The crate for a puppy is much smaller than the crate will be for the same dog when he is full grown. Unless you have an unusually large breed (we're talking Great Dane, Great Pyrenes or Saint Bernard here) then you probably don't need a crate very much bigger than a cat carrier right now. So do some reading on exactly why you are using the crate (it's not just a cage) and how to communicate with your dog. Watch a few episodes of Dog Whisperer on NatGeographic Channel (Cesar Milan). And realize that if you put in a little time right now, you can have YEARS of enjoyment later. If you don't.. you will ALL suffer from an unruly animal that no one will enjoy being around.
I was the last one who wanted to get a dog at our house (though I do love animals, I just didn't want the extra work), but once we decided to go for it, I jumped in full of excitement. You have to grab that excitement for yourself. It is quite rewarding to see how quickly your pup can learn new things (not just tricks, but rules of the household and his place in it). I never enjoyed having dogs in the house when they belonged to my roommate years ago. But our home would be very empty feeling indeed, if we were to lose our German Shepherd of 6 yrs. And she bonded the most heavily to me. No shock there, as I am the one who spent the time training her, feeding, providing vet care, walking her, grooming her, and just being home more often than anyone else. She looks after me too. And I would be a mess without her.
You can grow a bond like that with your new puppy, too. But start NOW and realize he is just a helpless puppy with no say in how he got there. Every moment of attention you give to him will be rewarded ten-fold with love and affection.
The alternative could be like my friend who let the husband and kids deal with it.... a dog who now jumps on guests, climbs up on the table and steals food right in front of you! She hates having it. But it didn't have to be that way.
First tip: Only take the dog out of the crate when you are actively involved with him. Yes that means that either a) he will spend a LOT of time in the crate or b) you will spend a lot of time interacting directly with the dog. But that is the only way to learn his "tells" before he is about to go potty, so you can pre-empt him and get him outside first. That is how he will learn to go out to go potty. If you let him stay in his own pee/poop (in his crate when you are out for long periods for example) over time he will lose his natural instinct NOT to "go" where he sleeps and he just won't care. And yes, at night he will probably need to be taken out once during the night. But it won't last that long if you are consistent and understand the essence of crate training.
Good luck. Feel free to PM if you need to chat more.