Vanashing twin Syndrome ????

Nanni

So today I went to my OB had an ultrasound and was told that one of the twins has a heart beat and measures at 7wks 5 days the other twin a heart beat could not be detected and measured and 6wks 5 days. I’m a little torn and don’t know how to feel. Not even a week ago both babies were fine growing and both heartbeats were detected. I’m confused they were both fine..... how does this happening could it be a mistake?????