Ex has children overnight on a Wednesday. Phoned Thursday morning to say they'd been in a car accident, were upset but unhurt and he'd dropped them to school. DS is only in 2nd week at school (not UK).
I felt like driving to school to pick them up but tried to be sensible and take his word that they were ok and to continue on way to work. Though in saying that, bear in mind he has tendancy to be v dismissive play things down
Ex texted later to say he had whiplash. I felt concerned for children and booked youngest into osteo as they had a cancellation appt available next morning. I thought I would see how older one was before booking her, partly because I am skint and partly because the younger one is super sensitive.
Left work at lunchtime, collected children who were obviously upset by accident but seemed physically fine, went for an ice cream and had a quiet afternoon.
Told ex had booked osteo and that youngest seemed quite off. Had an amicable chat and agreed I would care take another half day to care for him and that ex would take afternoon off to care for him then pick older one up from school.
All okay until midday when ex phones to say he doesn't want to leave work early after all and besides he didn't have a car, it was at the fixer's.
I was angry, said so, he said I was shouting so would hang up and he did.
I then shouted at DS, burst into tears and made everything 100x worse.
Took DS, who was pale and seemingly v tired, to school when he was fully expecting to go to Dad's. DS upset and I feel terrible, worried about work and worried about DS, v angry with ex.
Arrive at work and receive txt from ex saying he is home and can I drop off DS. I txt back to say he is at school.
Ex texts furious response saying I have wasted his time.
I won't go on but in brief there was a series of texts between us, all angry. I explained I felt he had changed plans, that I had taken 2 half days and was trying to act in children's interests and that really he was being rude and unreasonable. His lines were that he has a job, has a lot of pressure, and child is fine for school.
OK I do have a tendancy to be overprotective of my children. I always feel as though I'm trying to be a good mum as well as make up for their dad being a disappointment. So I know it is possible for me to be wrong, that maybe I was overdoing it to plan a day off for the youngest.
But he is only 5, new at school and has been in a car accident. Plus a giant weta nipped his foot this morning 
Not sure where to go from here. Felt anger like I have not felt in years. Have been separated pretty much since DS was born and our relationship has been increasingly amicable, we talk and text info about children and it's become quite smooth sailing.
But now I hate him all over again and feel utter fury at his cavalier attitude to the children's wellbeing. To put this in context, I arrived to pick up children one day and DS, then 3, was sitting on sofa looking pale and clutching his arm. Ex says "Yeah, he fell over, seems okay though." I took him to hospital and his elbow was dislocated.
Not even sure where I'm going with this... just very upset and wish to god the kids had a Dad who looked after them properly