Flamestrike
Legend
I 100% agree that it's too late, no issues!
But, future reference, you can give your inspiration to another player per RAW.
Pretty sure if you have inspiration, and you get it again, you can give it to someone else. Otherwise its yours.
Back to the attack:
The Gish has advantage to the attack roll as he is invisible. He also ignores Mirror image as he has True Seeing active.
Fighter: 12 or 6 (+9) = 21 - 32 Force damage. You still have a reaction if you wish to do something.
Rogue: 5 or 11 (+9) = 20 - 31 Force damage. You don't have a reaction at present.
Bard: 1 or 13 (+9) = 22 - 39 Force damage. You have a reaction if there is something you want to do.
Sorcerer: 19 or 20 (crap!) = critical hit! It would have been a critical anyway (it's a melee spell attack and you're unconscious) but ouch. 75 Force damage (and you're well and truly awake now, but Prone). From now onwards, you can take reactions (as you're now awake).
Cleric: 15 or 16 (+9) = 25. Another hit! 29 Force damage (and you're also out of reactions at present)