Wife assaulted me when I got kids for my contact

Hi advice please Am at NIsi stage with an informal contact arrangement which has worked pretty well although has been subject to change at last minute by STBX wife. I pitched up to collect my girls aged 6 and 8 and STBX demanded I keep them for longer than agreed. No prob with that but I had the nerve to suggest she arranged in advance as I have job to sort out. She totally flipped. I had my six year old in my arms as she had jumped up for cuddle and STBX started flaying out at me with kids overnight bag hitting both me and my daughter who got very very upset. She was swearing her head off and shouting. Kids both crying now.
I just grabbed my other daughters hand and got them in the car with her huing abuse
In car kids very upset saying they don''t wAnt to live with mummy any more as she shouting and snacking them a the time.
What do I do ? I don''t know whether to take them back after contact or keep them with me.
They obviously love their mum but am I putting them at risk returning them ? I don''t think she is beating kids up but they are clearly very upset.
Any quick advice would be appreciated.

Call the police and tell them you have been assaulted. If this was a stranger on the street, you would do the same. Your ex is not entitled to get away with this kind of behaviour simply because she was once married to you. You also owe it to your children to do this and to protect them.

Thx that''s what I wanted to do but worried about how she will react and whether I should take girls back or keep them with me

I imagine the police will be able to advise you about that as your children were involved in the incident. Whenever there has been a dispute of this kind between my stbxh and i the police are obligated to inform childrens services that there has been a domestic incident and i get a courtesy letter informing me they are aware of the situation. The incidents between my ex were never as severe as yours so i imagine it will be dealt with differently and hopefully fully investigated.

Thanks for that. Have appt with police this afternoon.