Husband having an affair

I think my husband is having an affair with his boss. He started a new job several months ago. Since then my husband and this women have grown closer and closer. They email out of work hours several times a day including weekends. He was even emailing her a matter of hours after our daughter was born whilst I was still in my hospital bed. He's introduced our new daughter to her and this woman gives him so much positive attention and constantly tells him how great he is. Not a day goes by where I don't hear him gush about what she had said or done this day. Am I just being jealous and unreasonable or should I be worried?