Dear Diary July 12

Dear Diary,
Today is July 12. I wrote earlier today in hopes that it would help me come to a decision. Should I or shouldn't I tell my best friend that her husband cheated on her about a year ago. apparently he cheated many times, one time witnessed by my husband, and the other times were bragged to my husband. I can't even talk to her very long on the phone. I feel that I should tell her, but they are happy now. It almost seems as if this is someone else's life. She does so much for him and this is how he treats her. If I tell her, our friendship may be lost. I know that my husband's relationship with his friend will be lost forever. this guy will try to fight with him since he's a jackass. I feel so stressed out. I feel like everytime i talked to her, that i was lying to her. and i guess i was. they are trying to have a baby now. apparently he hasn't cheated since they have been married. but that;s just not good enough for me.