I would tell him just that. That you don't have words to say, but that you want to connect (and possibly something like if there is some way I can help let me know - I used to think that was a crapy useless thing to say, but I've found in life now when someone says that to me -usually about the divorce- I do actually have something I ask for... - laugh - not that anyone gives it to me - but there may be some way you could help that he knows of).