Sorry it came to that ... and yeah your W is going to be pretty hot for a bit .... let her steam, You did not ask for this, and you did not go 'Dawgy" on the dude either (He beat the living daylights out of an OM and that term has just stuck) ... you simply gave him some truth and now its time to see where it goes ... most likely OM crapped himself and will run for the hills, but we will have to wait and see.
Right now your W is blaming you, you just stole her of her dreams and happiness .... BUT you also stood up for your M and your family which is respectable ... she will not give you this at the moment so you must hold firm, you will not live in an open marriage and if she wants to throw rings at you and file for D there is nothing you can do to control that, you can control how you react to her spew ... Get a Spew Jacket and prepare ... this is going to be a rough weekend .. hang in there and stay strong.