It isn't really very nice to knowingly hold back information that might potentially upset your DD. Put her feelings first.
What about suggesting to DD that she could ask her DF of he's bought his ticket because they might sell out soon? This would keep yourself out of it and let it be more about their relationship. (I probably wouldn't suggest something like this if she were younger, as I don't think it's fair for parents to 'pass messages' through their DC, but she's 9 and it would have good intentions - it wouldn't be passive aggressive.)
I understand how angry you must be with him. However you need to put dd first. You'll kick yourseld if he breaks her heart. Much as I HATE my ex & what he did to me. As far as dd is concerened even if I have to take the wrap her dad is a doting father.
Back Story. ExH left in July after having had affair, is having on off relationship with OW (she is still with her husband who knows!!!). She has DD in my DD's class who has physically and verbally bullied my DD (documented by school) they claim to not understand it. ExH phones up and shouts at me on Christmas morning (he has DD for Christmas) because I don't have his tenants phone number and she hasn't paid the rent for 2 months. So the school is doing a Dance Show in March which both girls are in over three nights in a small professional theatre. So yesterday I logged on to the theatre's website to discover that for each night there are only about 20 tickets left. I have booked mine. I felt that ExH and OW both have details of show and whilst I know neither of them will have looked at website as they are both as rubbish as each other, that I just am not going to contact him to say there are only a few tickets left. Now I know DD(9) will be very disappointed that her daddy will not get to see her dance. However, at some point I have to stop covering for him. I was fine about it until today a friend said "oh that's really not in your nature to be like that".