If she has no right to enter the UK it's unlikely she will be able to make any claim on your UK assets.
I'd just cut all contact with her and not respond to any attempts at communication.
Obviously this won't recover any Thai assets you put in her name.
Sorry, just read the post where you say she's in the UK.
If she starts a divorce in the UK, she will be able to get half of all your UK assets, including your state pension. There's a good chance she will also be able to claim assistance for any legal fees, which you may be asked to pay in the end.