Why Does My Friend Always Have a Worse Story Than Mine?
Attention is a limited resource and people compete for it without ever deciding to. Your story keeps getting topped because of: 1) conversational narcissism, the handoff from your situation to his happens on pure reflex before he hears the end 2) competitive victimhood, suffering works as currency in his head and he is not going to be outbid 3) the false consensus effect, because he sincerely believes matching you is the same act as understanding you. You were not looking for advice or a rival. You wanted a witness.
The pattern
Your story opens, his interrupts
Suffering becomes the currency
He calls that relating
You quietly stop telling him things
Where the airtime goes
Tell him something small and see whether it stays yours.