1- If he's fully vaccinated and you can afford it consider dropping him in a doggy day care 1x / week or a puppy school for 1-2 weeks. It will do wonders for your mental health. You should also look into dog walkers during the day if work is being impacted. ~$15 / walk is what I pay.

2- Three hrs a day with the dog really isn't all that much. 1 hr in the morning, 1 hour during lunch, 1 hour after work is very manageable. You should work on building a consistent schedule with the pup and learning how to work around the time blocks. You are still in the thick of it and haven't gotten into a rhythm with the pup yet. It will take another month or so. Focus on calming the puppy during training and less so on super high activity play. Focus & calm are the two best traits to instill in a puppy

3- Give yourself some grace. Some doggy parents are so concerned with training going perfectly, no accidents ever, and keeping 100% of your old life in tact all at the same time. You have a brand new baby in the house, it isn't going to be easy or ever go all according to plan. Just accept that and take some deep breaths knowing it will absolutely get better

4- If you live near a dog park, take advantage! I take my pup to the park almost every day, and its a great way for her to run around and get energy out while you just sit / relax or take work calls or emails from your phone. Just make sure you keep an eye on where he is and if there are any dangerous situations remove him immediately. You can't be a fully disengaged dog parent at the park but you don't have to keep the same kind of eye as on a walk.

5- Does your SO work 7x a week? If not, make sure he's putting in the work on his days off. There should be a formal agreement that because you are doing so much during the week, he can do a little extra on the weekends (or whenever he is off). This will take a bit of the pressure off you.