Have namechanged for this.
There's a long backstory re: my ex and his new gf that is too tedious to go into, but suffice to say the coparenting relationship has totally broken down since she appeared on the scene, and I've had to involve the police due to him sending me threatening emails.
The dc are with their dad this weekend and I have just received a message from a friend/acquaintance saying she wasn't sure whether to tell me but would want to know herself. She saw my dc with dad and gf in a supermarket and said she couldn't believe how gf was speaking to my youngest (7). She apparently raised her voice and said he couldn't have something he was asking for as 'that's why your father gives your mother money so tell her to buy it for you'. Friend was shocked at how nasty gf was and went in to clarify that ex was standing next to her nodding as she shouted at him.
For the record this month was his first ever CMA payment after paying nothing for 2 years. He pays £35 which would basically cover their school dinners, but I'm actually saving it for when they're adults.
There's nothing I can do bar keeping an eye on this is there? I consulted SS last year re: her being around the children (other issues/her actions made me believe she was unsafe) but they aren't going to be interested in this.
Contact us court ordered via a CAO, part of which stipulates that ex and I are not to speak negatively of one another in front of the children, but she isn't bound by this.