Gg2
19...Ra2
I'm so sorry, the Guard should take - attacking the Queen
21. Gxe2 Rxe2
and I forgot to update the captured pieces below the board in my image
22. Rxe2
OK, here's the sequence of moves to make sure everything is clear:
21.Gxe2 Rxe2
22.Rxe2
And continuing 22...Qxc3
Yes, you may still castle. Your king would move 3 squares (rules in the introduction).
Here's my (forced) move:
24...Kd7
You're not in this game. Would you like to start a new one and play?