ho hum, you've had 40+ years of not having this info, which lack of information you obviously prefer. But what if you Preferred to know? How dare he deny you of this information if you actually prefer to know. So he can't win, he can't presume which knowledge status you prefer without giving you a choice.
The "win" here is retroactive. He can't have a "win" now, because he's just fucked up really badly.
He could have found out - as OP told us - at any point during OP's childhood, when having medical tests/check ups etc.
Had he done so, & found he was not OP's bio father, she could have been told kindly & appropriately, as a youngster, while her mum was still alive. Parents presenting a united front, telling OP that dad chose to stay & chose to love her as his own.
He chose not to do that.
That's fine & dandy, but now the opportunity has passed, he's changed his mind & was comfortable with wounding OP - his CHILD, no matter the genetic facts - in order to satisfy his selfishness.