Some general thoughts:
I've had an intense job most of the time I've had kids, with particularly intense phases in the last few years as they got into upper elementary. I am now a RIF'ed federal employee with lots of time on my hands all of the sudden, and it's been an emotional journey realizing how much more time and energy I have to give to my kids now. On the flip side of this, I have too much energy for them sometimes and find myself raising things with the school or putting effort into things of questionable additional value, simply because I have lots of time on my hands and I am a little bored. The middle ground for me between intense employment and my current unemployment would be a less stressful job that didn't follow me emotionally after normal business hours or require me to work evenings and weekends on occasion. Or a part time job where I could protect afternoons, evenings, and weekends. If you have that available to you, I'd strongly consider that option, especially if you see the option to ramp back up professionally in 8-10 years.
For activities, you need to decide what you're going to let your kids do -- specifically the effort and toll it will take on the family vs the benefit to your kids. We have turned down lots of activities because they didn't seem worth it. Don't let yourself get sucked into the enrichment/acceleration/travel team thing and pack your kids' schedules or at least try to hold off a few years before you go down that road. They're better off hanging out at home with a not-stressed-out parent in the evening than being shuttled around to a million activities. Buck the trend and fight for your peace.
Consider what help you can pay for. Once my kids were in mid-elementary we hired a babysitter to help with afternoons and getting them to activities. It helped but required admin effort on our part (payroll, explaining logistics to babysitter). My kids are old enough to come home and fend for themselves for 30-60 mins now so we likely won't do that anymore once I am working again. Their activities usually don't start until 6 so we can come home and then take them somewhere. But the activities still mess up an evening (no dinners together or late dinners together is the choice plus later bedtimes).
Back to your question, it can definitely get easier over time, especially if you guard your time and sanity and accept you'll have to phone it in sometimes. The school emails, etc, can all be dealt with in chunks at a designated time every day or two -- you usually don't need to be responding to them in real time or during the day. One thing that helped us with the scheduling and emailing frenzy is switching to sharing google calendars between my spouse and me, and also getting a digital wall calendar. Streamlining as much of the scheduling as possible and being more efficient there has helped quite a bit.
Find areas where you are willing to compromise other things. Can you make your dinners simpler? Are you willing to eat "kid" foods? Can you phone it in a little on how clean your house is? (we love our roomba and have a cleaning service every two weeks but our house can get pretty disorganized in between). Are you and your spouse sharing the load in a way that feels equitable and doesn't leave (just) you sucking wind every night?
I thought at this point my regret might be that I worked and didn't stay home but it's actually just how hard I worked and the standards I held myself to. I also made no time for myself and had no social life -- developing some better friendships and activities has been the second best part of my unemployment, after getting to spend more time with my kids.
Hold boundaries, protect your family's peace, ask for help, and accept you need to do a mediocre job on some things.
Good luck!