"You fell victim to one of the classic blunders. The most famous is: Never get involved in a land war in Asia. Only slightly less well know is this:"
Sometimes, one needs to do unthinkable things. I am sure that similar things were said back around 1942 and 43 regarding retaking Europe. But if the PRC took SE Asia (including the Strait of Malacca and Indonesia) then we'd have no choice but to try at some point to take it back. War is hell.