Manipulative Ex & CMS claim threats

Hi there, new to the forum. Long story short me & ex been split 2 years now & for 2 years have had private arrangement & essentially have 50/50 share daytoday care of my 2.5year old. I also look after her 10year old (his dad is absent so naturally always have taken him on as my own). We work with a 2,2,3 weekly schedule so everything is right down middle with both kids.

Since January, ex has been asking me to lend her money etc. fairly regularly which i've always rejected and said no your debt is your debt. In april she asked me to lend £1,000 & she said it was to clear debt on sons nursery account as she fell behind few months i refused (she fell behind as she spent her money on a holiday to US with her ex).  2 days later after asking me for £1,000 i got a jet2 txt confirmation saying she'd booked a holiday- and conveniently it came to £1,000. She has asked me again a few weeks ago for help and i said no and she told me the state she was in- maxed out numerous credit cards etc. etc.

Anyway i've maintained my stance and to my surprise i got a cms letter saying she'd named me in a case- called them up & told them our arrangement- confronted her about it and she openly admitted she did it to prove a point that she can get what she wants. She backed down and called them to cancel it. Got records of messages of her apologising sayimg she shouldnt have done it etc.

Fast forward 2 weeks later and now shes saying she will quit full time work and go part time as she cant afford to live and will go CMS again and change story and say she has kids most of the time now shes part time (i've maintained il just pay and keep little one in nursery for my half the time- so when its her time at home and shes off she can just have them- no nursery bill for her and its reduced her costs/doesnt change our day to day arrangements) but in her head- she wants me to pay little one in nursery my half the week (rightfully so) but then additionally pay her when she has the kids her half the week because she's decided to stay at home (her choice because of her circumstances)...

This is all motivated by her own loan/credit card debt and because I've refused to help. I know i need to speak to CMS- but should i be escalating this further- as shes essentially using it to 1. control me 2. claim under false pretences- has anyone experienced similar? Sorry for the long post- but never expected to be in this situation or subject to such manipulation & given how delicate the situation is (shes a big narcissist and very aggressive) just wondering best course of action.