Blac Chyna -- Tyga Hacked My Twitter ... I'm Not a Gold Digging Cheater!

Blac Chyna is blasting her ex, Tyga, for pulling a hack job on her to tweet messages where she appears to confess she's a gold digging cheater.

The tweets -- sent early Sunday morning from Blac Chyna's account -- said, "Im a gold digger & a cheater. I never really loved Tyga It was always about the money. After he took me out the strip club gave me a beautiful family."

Of course, BC denies being a gold digger or a cheater -- and she quickly posted an update on her Instagram saying her account had been hacked by Tyga. Shortly after that .... the tweets were gone.

We've reached out to Tyga's rep ... so far no word back.