I read it about 10 years ago,cannot remember who the author was. The main characters were a teenage girl called Apolonia (Api for short),an architect called Bryn and his wife Linda. Apolonia came from a rather dysfunctional family,and had a brother who was mute by choice. There was also a woman called Miriam,who I think was Bryn's sister. The book was based around Bryn designing a memorial for children who were holocaust victims. And I can remember that Apolonia committed suicide.
I know MNers are good at sussing out books. Any ideas?