Every time travel story where the traveler can go into the past has one inherent flaw, illustrated by this episode: If you change the past, you change the future.
By killing his younger self, the protagonist also eliminated his own future--including the one where he was able to travel backwards to the past, and kill his younger self.
Also, he even being able to co-exist with his younger self in the same time-space comtinuum is a paradox: how could he be there before he was there?
Makes your brain hurt, right?
No wonder he had headaches and hemorraghes.
I saw this one coming a mile away. The "fatalistic" concept was telegraphed early on. The ending did not solve the conundrum. It simply ignored it.
I'd have "bought" the premise if he went back in time to when he first met his wife, and armed with prescience (don't we all wish we had it?)--being able to "do it over, knowing then what I know now"--he had relived his life from that moment forward, incuding not inventing the time machine.
Of course, then there's the paradox again...
Maybe Einstein was right, after all: you can go forward, but you can't go back.