She wanted to sleep w/ my husband & now she is cheating on hers?

I met her & her husband 1 yr ago. her hubby adores her. She was giving my hubby lustful stares, innapropriate comments, etc.. My husband is oblivious and he even noticed it. We just chalked it up to her hav. a crush. So, we moved away for 8 mo's and came back & reconnected. we were so happy to have them back, b/c of interests fun, etc.. so, she goes away for many weeks to training(for her job)& comes back & tells me she cheated w/ this guy and cant wait to do it again and she doesnt feel guilty. so im trying to councel her by giving my life experiences and my mistakes, yet slipping in consequences from time to time.. no reaction, she just keeps talking about the . I try not to judge, we've all screwed up. but now im thinkin bout her poor sweet hubby. then she says she gave ual looks under her hat to this guy at training so noone would see. at this point i FLASHBACK to when she used to do that SH** with my husband. So, now im thinkin i CANNOT trust this person EVER.. RUN!!! i went home told my hubby and he was FLOORED. my husband wants to tell her husband b/c he is a loyal friend to him & feels SO bad for him. she wants to stay w/ him, but just sleep around. We feel like she is cheating him of his right to happiness (she wont even let him touch her now) Geez, when I saw him he looked SO SAD. (he knows something isnt right) So, my question is do i try to be her friend and try to councel her or cut ties and us tell her hubby?