Margaret Mackintosh, aged 56, met Tobin in 1969 when she was 17 and told The Times she suspected him of raping and murdering girls while they were still married.
She said he once attacked her with a knife, surviving only because a neighbour who lived below saw blood dripping through the ceiling.
She said: “Very probably he has killed dozens. It wouldn’t surprise me at all. There were times when he went out of the house for an hour or two at a time, left me locked up and I had no idea where he was.
“It’s easy to say it with hindsight, but every time he came home he would always be very aggressive.... he would rape me just for the hell of it. I got away lightly because I lived, even though he left me for dead. I was just lucky he didn’t bury me under the floorboards, alive or dead.”
Ms Mackintosh, who is now happily remarried and living in the Highlands, said she fled Tobin after a year but still bore the mental and physical scars.
Tobin was 41 when he married his third wife, Cathy Wilson, now 37 but 18 at the time, in Brighton. A year later their son Daniel was born.
She told the Mirror of her horror at learning police found Vicky Hamilton’s skeleton hidden beneath a sandpit Tobin had dug for Daniel to play in.
“This is the most evil and despicable thing ever,” she said. “Basically a play area was created for him to cover up a murder. All his charm and warmth disappeared the minute I was pregnant. He was violent on a daily basis.
“When I saw Angelika Kluk’s picture, it frightened me how much she looked like me when I was younger.”