Instructors who break marriages

I take full responsibility for my part in this- but I slept with an instructor and it was the virtual end of my marriage. I’ve come to find out that this man has a history of sleeping with married women. He has broke up several marriages including the one with another jiu jitsu practitioner who is now investing probably thousands upon thousands of dollars to open a gym with her. I am having a bit of a bad conscience wondering if I should find a way of telling her that she’s a part of a long stream of women he has done this with before she spend what is probably her life’s savings to start a business with her. If I do… how do I do it without her knowing it’s me???