How do u help a loved one who is being cheated on?

My aunt just found out that she is being cheated on. She has been married for 23 years, and i feel that she suspected instances before, but only now found out for sure. My uncle has not denied nor confirm his infedility, yet tells my aunt that he will do watever it takes to make her happy..includin a divorce. She confided in my mom and i but doesnt want to tell my gmother, her mom, as she will, as past experience proves, only make her feel as if the world is comin to an end and cause her more stress dan ever...she mite even say my aunt is giving her stress!..she did it on other occasions...with other ppl and my aunt..she doesnt discriminate lol. my cuz, says he doesnt want to interfere, while his bro says he supports my aunt. how can i help her...wen she confided in us today she says she wished she had a daughter....but i have a bro and he definitatelty is just as emotionally supportive as i am of our mom..p.s. my mom went tru a divorce but i had afew months old wen she left my father because of cheating..and she remarried soon after..like 4 years..its heartbreaking to watch my aunt suffer..how can we help her without being manipulative and in a positive way to do wats best for her? My uncle made ual advances on my other aunt..his sister in law wen his wife was pregnant..and dey blamed her for it..said she wanted her sis to lose her baby...i cant say i'm surprise this happened..doesnt make it any less heartbreaking...