New Apple ID help

[AJ09]

My ex husband let me use his email address many years ago to set up Apple ID. Since then every phone I've had it's always been that email address.
We recently split and he's told me that email address is being deleted within 30 days and I need to change my Apple ID.
Is there anyway at all I can make a new ID up and transfer absolutely everything in one go? Or do I have to do things separately.
The main thing I need is all my photos, videos, messages and WhatsApp convos.
I'm not sure if there is an easy way to do all this as I'm googling it and it's showing me mainly how to set up a new ID.
I just wondered if I can transfer everything with it?
(And anyone who can help me please explain it like you are telling a 5 year old, that's the only way I'll understand 😂)

Does this help?

Could you get to an apple shop and see if the tech people can help ?

Your WhatsApp chats should remain because that works from your phone number, but back up just incase.

I’m not sure about messages if they’re iMessage. Are you close to an Apple shop?

You can change the email address associated with an apple ID, you don't need to set up a new apple id. I need to switch a phone to a different apple ID without losing anything and even that isn't too bad.

My closest shop is 30 mins away. PP how do you change the email address associated? That's easier for me than a new one if able

support.apple.com/en-gb/109353