How would you advise to safeguard myself as I am genuinely worried as she got me arrested previously through false allegations and wouldn't put it past her to do it again.
Safeguarding yourself.
You can get voice activated recording devices to wear as a necklace or keep in a pocket. I suggest you have one for any time you spend with the child or with your ex. Similarly you can use your phone and/or sat nav to record your location history. If you have video calls, use a screen recorder. There is a good one built in to android. So far as possible without looking suspect, follow up on any conversations with something in writing. Keep everything you write positive. Pretend you are writing to somebody reasonable that you can work with.
The above moves are all for insurance against attack rather than for you to go on the offensive. You will have a catalogue of evidence to defend yourself with.
In my personal opinion, the clever thing for your ex to do would be not to involve the police. Police need evidence and have a much heavier burden of proof for the person making allegations to satisfy. The wise move for her would be to make a load of allegations that cannot be proven or disproven for the final hearing. She can rely on a general reluctance to call the "victim" out instead of evidence. At a DRA allegations can be signposted rather than detailed to make the court act with caution. I wouldn't expect what she brings to the DRA to be her big guns.