Originally Posted by FullofLove1052
Nothing but abstinence provides that guarantee. [...]
The only feasible solution may be for the relationship to end.
What about abstinence from PIV sex while enjoying everything else, as others have mentioned? Is that something your husband and girlfriend would be comfortable with for the duration of their relationship?
Your feelings don't make you a bad person. While it'd be ideal to have known and stated your feelings before you went from a V to a triad, some feelings don't become fully known until trying things out and realizing the full implications.