I do concur with Kem (this is happening too often!!!) anyway, Danilyn, as he said, some people (especially women), don't/won't accept your warning. I also know from experience when my cousin's man, who was in college with me in the South, was playing openly, while she was in the West. And once she moved down where we were, she wasn't "allowed" on campus unless he escorted her there. She was blind and had all kinds of excuses for this strange behavior. When I told her straight out that he was cheating, she went off on me and accused me of all kinds of things. Including jealousy. This was hurtful because we were raised as sisters and had never fallen out about anything.
Of course she was embarrassed and ashamed of herself when one of his women approached her with an engagement ring.....
So it depends upon your situation. Are you willing to suffer the ridicule and accusations she might hurl at you? Or is she a reasonable kind of lady. (even the "reasonable" ones can turn when it comes to LUV). Weigh it out. But like Kem says... "seeing is believing". No doubt about that.
Handle with care, sis. If she was ever a real friend, she will always be.
a
ps oh, and that woman married the scoundrel but they soon got a divorce...my cousin didn't lose out at all