Will my husbands new relationship work my so called best friend?

I recently found out that my husband is in love with my best friend. We have been married for four years and during the past past month he started seeming distant. He told me he wanted a divorce because he was unhappy, then a few weeks later told me he was in love with my best friend who was having problems with her marriage. She has cheated on her husband for the past three years with numerous people , but now both my husband and her are convinced they are soul mates and are in love. They have been staying in hotels leaving the kids at home with me and her husband for the past two months. I have a 9 mo. old baby and a 12 yr old step son. She has two boys 7 and 4. I really thought my husband would stop and realize what he was doing. She is unreliable, a smoker & has a past history of being promiscuous, etc all things that typically he would not be attracted to. After two months they are ready to move in with one another. Does anyone think this will work? Are they in love?