I think it's easy to sit on the outside and say she didn't tackle it. She's already anxious (turns out rightly so) it's her first, and possibly only, pregnancy, and this is one of the key important moments.
*I think if my DH has said, I'll take one of the kids to a theme park instead, I'd be so "what the actual fuck" and trying to contain both anger and upset and flooded with hormones, that I'd probably growl something along the lines "Can't think of a better place for you to be, you have a lovely timeyou twat"
Absolutely! But this didn't come out of the blue, the night before the appointment.
Her 'D'P had already made it clear that OP and the scan were NOT his priority 12 weeks ago when the appointment was made. OP tried to change it but couldn't, and he didn't make any plans for his ds to be looked after just for the duration of the appointment.
*That" was the point to tackle it, 12 weeks ago. If my dp couldn't understand my anxiety, or accept my need for his support, I'd have spent the next 12 weeks evaluating the whole relationship.