How to cope?

LM :)
My brother in law and his girlfriend of 6 months just announced they are pregnant. Not planned at all. 
​Although i want to be happy for them and ensure them that everything is going to be okay and that This is the going to be the best thing happening to them, ever ... 
​... But inside i'm breaking. I just want to cry. I so wish it was me after 12 months TTC.  
​I can't cope.
​How do I deal with this?