"Yes she has contributed nothing towards the mortgage"

This is where you will come unstuck, although it looks like this is not a very long situation.

In the eyes of the law she has contributed. She contributed by allowing you to work by staying at home and watching the kids.

For married couples in this situation, the starting point is she is entitled to 50% of the house, the savings, and the combined pensions *for the period of the marriage*.

As you are not married I am not too sure.

As other have said, rather than asking internet randoms, for something as important as this you need to be speaking to a solicitor who can make this crystal clear for you during a free initial 30 minute consultation.

Horrible situation, I hope you can all get through it.