You need to take the ring off entirely. You need to exist as though she does not exist, a neighbour living in your house just waiting to move out.
Her cousin was not a bad influence, her cousin is just like her. Like seeks like. And yes, if your no good wife wants a divorce, give it to her. Give her everything that she must legally get, give her nothing more. She doesnt deserve your heart, so keep that for yourself.
Just cos things are going right, doesn't mean that they were always wrong.