OP I could have been you, down to ambitious and high-powered job, highly educated, husband with great career. I was happy to stay off as had a business plan I wanted to try out so worked for everyone (DH got to continue unimpeded, financially supported me to have a go at something else in spare time, dc got to see me). Circumstances dramatically changed due to Brexit, our lives are much more insecure due to his volatile industry, i took what I would describe as a unicorn job (very part time, very interesting, adding valuable skills in an adjacent hi-tech sector, highly paid, amazing boss, CV enhancing YES AN ACTUAL UNICORN JOB!). I left my 14 month old in nursery and used to drift in a sort of sad, anxious, squishy, broken, massively, massively sleep-deprived version of the Old Me, wracked with guilt at leaving my baby in nirsery.... 18 months on i am sooooooo glad I persevered!!!! I had to as I’d clearly never have got such a perfect opportunity again.
What helped me were things like: building great relationships with the women at nursery. I had so much respect for them, many of them were working mothers themselves and were so amazing and supportive to me. I say overwhelmingly women but they had a couple of great male staff too. But when we moved I got a great childminder and never looked back.
Also, just realising that I had been very privileged to take so much time off, that I was still privileged to be so part time, that I was a professional woman and FOR my children needed to be back at work maintaining if not accelerating my career, earning pensions etc. That we live in an increasingly insecure world and that even though I spend virtually all my pay on a complex web of childcare (we need backup and I also pay for a day where I continue my slow-burn business idea), if my husband got made redundant tomorrow which is now not unlikely, I could just about support the family and could in fact quickly move jobs or ramp up to support them properly.
Sorry, a lot of information, but your post really chimed, and being on mumsnet as ever reminded me that I had it so good, my kids have it so good, that you have to think of the long game as well as the short, that while I respect staying at home as one of the most difficult jobs certainly I have ever done, I am MUCH more suited to office dynamics, so am happier too.
Hang on in there, the first weeks are hard but if you like the nursery and her carers and you devote yourself to them the rest of the time, I think you’ll be fine.