Life and love can be very hurtful at times, but I firmly believe the hurt can make us stronger and better for it. Reiver...The worst thing that you could do is to beat the lad up as this could lead to long term emotional problems between you and your daughter. However, if I was in your situation I would be wanting to have a quiet word with the lad to let him know how much he hurt your daughter and the rest of the family for thay matter, and if he thinks it could happen again to bugger off now rather than cause more hurt later..
thanks for all the advice lads - ultimately I don't think it matters what I do as given that he has done it once I suspect he will do it again and that will be that and I will be there again to pick up the pieces. I obviously won't knock him out no matter how much I want to - as the old saying goes "he's not worth it"!!!
The sad truth is, I have a son and have seen a few broken hearts, most from the same person, but all we parents can do is be there, let our kids make there own mistakes and be there when needed. Remember how we always knew better than our parents, nothing changes.
Usually ends up like.. [video=youtube;pc0mxOXbWIU]http://www.youtube.com/watch?v=pc0mxOXbWIU&feature=related[/video]