Vanishing twin?

Carlie
Today we went for our first ultrasound at 12 weeks, we seen one happy healthy baby measuring 12w+4d.
​However, there was a second baby there which didn't have a heart beat and was measuring 9weeks.
​We obviously had massive mixed emotions, happiness at the healthy baby, shock of twins (none in the family), and sadness of loosing one.
​We have got a consultants meeting on Friday and are now considered high risk, need another scan too because they couldn't clearly see if they were sharing a placenta and/or sac. 
​After a bit of google research it appears to be called 'vanishing twin', I just wondered if anyone else has experienced it?