It was amazingly sad the moment you could just see Tyrion break.
Once Shae walked out as a witness for the crown (is that how it was titled?), you could see the shock and disbelief. Then, as she started talking, the moment Tyrion sits down you knew he was done.
I imagine Tyrion has taken a lot of punishment (both mental and emotional) for the length of his life, but this was the one that finally broke his spirit. I was fearful this would happen and it did. Simply killing Tyrion in this show wouldn't be bad enough. It would have to be something just absolutely soul-crushing.
Shae was the one thing in this shitty, lie-filled world that gave him any hope for a potential happy future. Yeah, he sent her away- but I think for him just knowing she was alive somewhere, safe, was enough hope for him to hold on to... hope that one day he could fly away from Kings Landing and be with the one person that makes him happy; the one person that doesn't make him feel like an "imp".
That's all gone now. All of that love, trust, and hope built up- just destroyed down to the foundation. Even the best scenario for Tyrion, a champion winning his innocence, isn't going to fix that.
A woman that he deeply loved betrayed him. His family (sans Jaime) betrayed him. The people he protected and risked his life for laughed at him and mocked him. Decent people he met on his travels are either dead or long gone.
Out of all the deaths in the show so far, the death of Tyrion's wit and spirit is probably the most difficult for me so far. His final "Fuck you" speech just seems like a man accepting the fact that he's a dead man walking... and that's just heartbreaking for me.