Entered into commonlaw in 2015.It was her home,I matched original down payment.In 2017 I left relation and only got that amount back. How do I record sale of residence?

Was the house in your name also?

Yes.   My name was added to the title when I moved in with her.  I only asked for the amount i put in,  not based on current valuation

You will then enter it as you owned 50% of the value of the house. Then deem the disposition as your 50% - which you'd be entitled to since you were actually buying the house since your name was on the deed.