Die Hard...I didn't have to chose winning the South...it's what I, my Brother (decorated Navy Seal and US Marine), and my Father (a Decorated WWII and Korean War Veteran)...DID...from 1965-1975.
You defended the South. I'm afraid you didn't win the war, but that was not your fault. You were never meant to win the war, only prevent the South from losing. However, even that became an impossible goal; not militarily, but politically.
It was McNamara, Johnson, and cronies who only saw maps, and not peoples, who feared China and the Soviets.
Anyone in their right mind would fear the Soviets at that time. McNamara and the others were staring down the barrel of 10,000 Soviet nuclear warheads at a time when Khrushchev had said his famous "we will bury you".
You're right. You didn't have to make that choice. McNamara, Johnson, and "cronies" had to. And they made the right one. South Vietnam wasn't worth starting WWIII over, and after several years of watching body bags coming home from Nam, public opinion in the U.S. no longer supported sacrificing American lives to simply hold the communists back in some backwater swampland in South-East Asia. The only viable option was to pull out.
It was never the intention to invade North Vietnam and defeat them. Just hold the South, bomb the North, and hope they would give up. You, as a soldier, was never given the option of winning.
Heck! Nowadays I'm not sure that anything I say won't hurt someone's feelings...
Relax. I don't think you've hurt anyone's feelings. I can imagine this is a very emotional subject for you. I can understand your earlier outburst.