DH and I got our first dog (first dog together, we'd both always had dogs as children) when I was pregnant, but further along than you just at the 'tail end' of morning sickness. Looking back now (28 years and numerous dogs later) we both agree it was a mistake. We persevered and she was a wonderful dog (Golden Retriever) but it was very stressful for all of us, including her. Not just housebreaking and obedience training, but also having a pup and a newborn. And my DH was fully invested in caring for her. You apparently aren't that lucky.
I'll pass over the 'DH won't let me return' because unless you think he's going to physically/mentally/financially abuse you if you do (and that's a whole other issue!), returning the pup is in your control. You call the breeder and return the pup on your own. Done!
If you won't return the pup then you will need to persevere. But a lot of it will depend on where you live. We had a house with a fenced yard, so it was a matter of my taking her out on a lead to the same spot in the yard after every meal and about every two hours during the day and sitting there until she did her business. Obvs if you don't have a yard, that means a walk to the same spot every two hours OR training to use puppy pads if it's a small dog. But the key is that you have to be very alert and proactive. If you aren't, then what you are doing now is setting up the scenario where pup thinks it's OK to 'go' in the house. AND you are creating a nervous, fearful dog if you are shouting or punishing for it.
If you don't have a crate, get one. Crate training is easy and dogs don't like to soil their own 'space'. It's not a miracle training cure, but it does seem to help with 'night training'. Plus a crate trained dog looks on its crate as its 'safe place' and that makes it easier to contain the dog for deliveries and such. Or for you to get a break for a few minutes. But do NOT think that you can get a crate and then leave pup in it for hours a day. That's cruel.
For now, if you won't rehome, remember that the days will pass and you'll hopefully feel better soon. Just remember that the pup is an innocent, sentient creature. He doesn't realize what he's doing is wrong. It's your job to gently teach him.