UPDATE: We got an email from Lauren's lawyer, saying "Many of the statements [in our story] are simply inaccurate," though he does not specify which. He adds the parties are trying to settle the case confidentially, on a "private basis."
Lauren Silverman -- the woman who is pregnant with Simon Cowell's baby -- is telling close friends she is outraged at her estranged husband's "shock" that Simon was banging her ... because she says he knew what was going on the whole time and he was doing the same thing.
Sources close to Lauren tell TMZ ... Lauren is bitching that she hooked up with Simon partly because her estranged husband Andrew Silverman was cavorting around the world and partying with girls on various continents.
What's more ... Lauren is telling her friends her relationship with Simon evolved right in front of Andrew and he never said he had a problem with it -- it was a tacit mutual understanding.
Lauren is saying she would speak to Simon several times a day on the telephone and Andrew knew they were talking.
Lauren says she visited Simon in England several times and Andrew had no problem with the trips -- and it was obvious what was going on.
Lauren is beyond pissed that Andrew is now feigning shock, because she says he knew everything from the get go.
As for their divorce, Lauren is telling friends, there are no real money issues. The real sticking point is their 7-year-old son. Andrew wants full custody but Lauren is saying no way in hell will he get that.
In fact ... Lauren says she wants primary custody and will fight tooth and nail to get it. Although she admits that she sometimes travels, she says he is away much more than her and she is the better parent.