For what possible reason would you tell your fiance?
If you do tell her, both you and her will feel like crap, and you'll likely break up. If you don't tell her, only you will feel like crap temporarily, and if you wanna stay with her you still can.
You have nothing to gain and everything to lose by telling
My 6th grade advisor used to tell me "honesty is the best policy"
was she wrong? Does my fiance deserve to know I'm a cheating ho bag even tho I love her and treat her right?
What actual benefits would you get out of telling her? How would it benefit either you or her?
If we broke up I could fuck 919s without feeling guilty.
You still can if you don't tell her and choose not to feel guilty.