this drama!

First off im writing this anonymously to prevent damaging this persons reputation , the LITTLE she do have....soo my "friend" which is a older lady exactly 20 years older than i am , has 5 kids & unhappy in her marriage & cheats on her husband basically with any man she can get her hands on. So just recently she started attending my family functions & i noticed that she made a instagram & started to follow two of my brothers. Then she slipped up & told me that she texted both if them. I tolded her that it made me really uncomfortable & i wanted her to stop , she simply told me she would because she cherishes our friendship. Soo months went by & i got a phone call last night & it was my brother bragging about how she picked him up last night & how she slept with her and all....sooo now im pissed & not only that it's causing problems in my family because now both my brothers are mad at each other! & that's a big no no. Moral of the story is yes i know we're all adults & both she & my brothers can date/fuck whoever they want. I just simply feel uncomfortable because i sit in her house, play with her kids, have game night with her , her husband & other friends. just simply makes me feel uncomfortable, im ready to break off this friendship because of this. She's broken my trust & im just disgusted.

What should i do???