I'm torn, what should I do?

Obviously we cant answer this and i suspect you know this maybe a matter for your heart hut feeling it isnt fair to label her a repeat offender type ppl can and often do change but as she hadn i understand you all i can say is most every family believe it or not has very many problems like yours and is as well dis functional only you know whats best the others are grown up so not to much damage but there is the young ones there very vunerable need to think of whats the best option for there future and well being you pedo like a caring lovimg grandparent good luck