Well, let's just think of some famous OW. Like Cleopatra, Queen of Egypt. Topped herself at the age of 38. V jealous of Antony's wife - not because he might love her more, but just because she had that status. Well, according to Shakespeare, anyway.
Anne Boleyn - she got the chop within 3 years of ousting her predecessor.
Nell Gwynn: despite Charles II's famous deathbed injunction "don't let poor Nellie starve" I believe that's just about what she did.
There aren't that many famous OW because they tend to stay in obscurity.
An acquaintance of mine carried on a clandestine affair with a married man for years - decades. Eventually the wife died, and the OW hoped the man would marry her. He didn't. He liked having a secret lover so he kept her so secret that eventually when he was dying, she couldn't go and visit him in hospital in case she ran into his family. When he died, she didn't have the position of grieving widow even though she felt like one, and couldn't go to his funeral.
A secret, guilty relationship has its repercussions.