'ditched him' is correct and can be used in written English.
You can use it to mean "abandoned him" or "rejected him". For example, "She ditched him after his embarrassing behavior at the party."
How about Reader, I ditched him?
They stopped awhile in England, but his eyes kept running and they ditched him.
Then the elder fell briefly ill, and Sarkozy ditched him to enter the race himself.
Mr Rudd's party, in turn, ditched him as leader when he walked away from that plan.
We backed George W. Bush in 2000 but ditched him for John Kerry in 2004.
She ditched him for excitement and glamour; she's settling for EastEnders and coffee creams instead.
There seems little mileage in ditching him.
When she ditches him, he obsesses about her in ways that seem normal until they become destructive and then violent.
But Duck, the bastard, deals with it by frogmarching Chauncey downstairs and ditching him in the murky Manhattan streets.
At the party, things are going O.K. in spite of the red-haired girl ditching him first chance she has, hooking up with one of the older guys.
Mr Brown survived only at the discretion of his colleagues, and less because of his virtues than because of the risks of ditching him.
