No Matter what you do in this hobby, no matter how careful you are, at some point something is going to bring a craft down, IF you and the P40 guy are okay with each other then that should be all it has to be, I agree 100% that a good laugh and a coke (pepsie) should have been shared with each other because that is what this hobby is all about,, Good times, good laughs, and the ocasional why didn't I do that instead at the last second, makes this hobby the thrill that it is for me.
I have been in quite a few good mid air collisions, and I always say I'm sorry as we approach the carnege usually in awe and laughing about how cool that just was, and I usually get one back as well, But we have always enjoyed the crash as it happened, as we know its just part of the hobby, I am always sorry to see someones plane go into the ground so I always say I'm sorry, but I Always let them know just how cool it looked and especially in a mid air, I usually imediately start laughing and try to get the guy with me putting on a smile as we watch debrie fall from the skies.
I fly with a great bunch of people though and we can't preach enough to the new people joining us that no matter what,,, we are here to have a great time, and everyone at our club anyway is more then willing at anytime to help someone rebuild or give parts to someone who is in need of getting back in the sky. Even if that means handing over a plane for them to fly for the day, You just can't ask for better club members then that, I know many clubs don't have that, but they should, were all in this together, we all know what its like to lose a plane, and I know I'm going to lose another one sooner or later, my only wish is that it doesn't hit someone when it does and I hope I can view the crash for entertainment purposes.
I say sorry for you and your friends loss, now break out the Zap and epoxy and have a good time building another plane or rebuilding that one. Maybe there is a fault and maybe there wasn't, who cares,,, once you bring a plane into the sky, its all about the fun while your up there, If I had a plane I didn't want to crash ever or break, I would hang it on my ceiling, until I knew nobody was around when i went to fly it,, then I would just smash into the ground probably, and no one would have witnessed it,, that would be worse... LOL
Good Luck and I hope everything works out Okay