I have had similar experiences.
The first thing I’d do/did was to ask her if she minded telling me what happened. Her reply is not as important as the fact that she was “justified” in being offended. I apologized to her as Christian. She said that I didn’t do it but my reply was that we are a body and so I am responsible. Again, I told her I’m so sorry.
I then asked her if she felt that Jesus would have done what the church did to her. She replied, “No, He wouldn’t have.” I then encouraged her to look to Jesus and not man because we always fail people. I told her that she should come to our church and I will guarantee that at some point, we’ll disappoint you too as man seems to be good at that. But I told her to make sure she realizes that Christianity is all about Jesus and not people. I mentioned that even Jesus’ disciples, after He had ascended, missed the mark and told her where that was in Scripture. So I again reminded her to keep her eyes on Jesus.