Married 4 1/2 year

Been married 4 1/2 years to a 60 yr old women, it’s my house and she only gave me £200a month , now she is divorcing me and trying to screw me over for half the equity in my house? What is the best way to tackle this please, surely this isn’t right ?

1. How long have you been together?
2. How old are you?
3. What are your respective incomes?
4. How much is the house worth and what is the outstanding mortgage?
5. When did you buy the house?

Whether it is fair or not will depend upon the answers to these questions. (And perhaps others but these are the most immediately obvious).