OP what does your husband actually think? You mention he won’t move, but what are his thoughts on you doing this specifically?
I am really torn here and truly nobody knows the right decision but you, and even then, perhaps you won’t know if it was right until after you’ve done it and can reflect.
People have many valid points about the dad, and I know we all want equality etc, but often the mother is the nurturing one, more so. That’s just how it is in reality. Dads who are very present still aren’t over the intricacies of school life or note really subtle shifts in their moods which could be due to X/Y/Z. As such, for me, the biggest thing are their ages. Entering secondary and a very complex stage of development. It’s harder for teenagers these days with social media pressures etc. Personally I would wish to be extremely present for that. I think anyway, easy for me to say theoretically.
Essentially you’re proposing the same set up as divorced parents in terms of how often you see them. Loads of children adapt. The difference if you technically aren’t divorcing so the children may feel a little abandoned maybe? I think you need to discuss their feelings and hear from them. They’re old enough to have considered thoughts - be prepared for it not being want you want to hear and if you would in essence go against it.
I am a career woman, I travel to the States every 2-3 months and can be back late from work on evenings. However I don’t think I could be away routinely for nights away during the week for two years.
I also think regardless of your DH husband to want kids initially and your reluctance initially, you ultimately had them. You can’t place resentment on kids for a decision YOU made. You weren’t bullied into your life, you should have considered your career when they were tiny and flexibility and establishing a baseline if ‘normal’ is easier. If you’ve always worked away they know no different - at 10 and 12 they do.
Is your marriage a happy one? Could this setup be the catalyst for a breakup? I wouldn’t wish to live apart from DH for this period of time. However in the event of a breakdown I would likely assume your DH would be considered the primary parent as he would live with them full time.
I was 11 when my dad worked away for a week during the week for a year. He came home weekends. My parents thought it best I finish year 7 where we lived and gave them chance to find a house in the new area. It was hard as I really missed him. I am however not traumatised from it and nor was I. My grandmother also went into a hospital and my mum moved to Scotland for 6 weeks to care for her when I was around 13. We saw her a few times as it is 6 hours away so much harder. That for me was far far harder even though a shorter period. I think perhaps as it was my mum and she was my primary caregiver.
good luck on whatever you decide.