difficult decision

Many many years ago, when my daughter was about to be born I though about a hypothetical very difficult decision. To cut the long story short my partner was taken to an emergency cesarean and I was left alone in a small utility room waiting. The hospital was being renovated and I think they didn't have a better place to store me. I spent, what felt like hours, pacing two steps one way and back. Thinking. No one came to tell me what was happening so this was the only thing I could do. Obviously my brain started to invent all sorts of dramatic situations. What is they both die? What is someone comes and tells me they can only help one of them and I have to choose? What would I do? At this point in time I didn't know my daughter yet. I spent most of my life with my partner and the decision was clear to me. I would have picked my partner to be saved. Children are extremely important to me and I would give my life for them but an unborn child is... not a child yet? This is harsh but I cannot develop any attachment to a person I never met. 

I told about this dilemma to my partner some years later. It wasn't easy especially that I already met my daughter and I loved her dearly. But the truth was, in the past, I would let her die to rescue my partner. 

What happened a few days ago though made me question my partner's sanity. She was very upset and brought this old conversation up.

x: Do you remember when you told me that you were scared that doctors would come and ask you whom you wanted to save?
me: Yes I do remember
x: Don't you think I know?
me: Do you remember what I told you?
x: Yes I do
me: And what did I tell you back then?
x: I don't believe you
me: What was my choice. At the time?
x: I don't think...

me: So you remember what I told you but you decided that I lied to you and you are going to cry about the imaginary lie? Contrary to what I actually said?
x: How can I believe your answer?
me: Umm because I never lie to you?

This conversation is real. My partner thinking process here is real. I told her a story about the most difficult day in my entire life. Years later she brings it up as a lie. Why would I made it up? What is the point of talking if everything I say gets twisted and turned against me? There was no room for misunderstanding here.