How do i break it to my friend that?

My good friend Melanie is very much still in love with her ex.bf they used to be best friends before they dated she never got over him and felt like eventually she would get back together with him because the new gf was just not his type(too meekin her opinion).Also she felt he was only with the new gf for his then baby son.Recently she began contacting him via email and she invited him to go out for lunch they talked she said she felt for sure that the connection was still there.She had a whole plan on how she was going to get him back before going to london on business.Well by the end of the week her ex.bf proposed to the mother of his son and gf of 5 1/2 yrs. How do i break this too her before she comes home?