She has been making passes at my husband

Good day mamas and papas in the house, please I need your help on how to handle this matter. There is this married woman that has been making passes at my husband. She has been sending him love messages declaring how much she loves him but he has been mute. Recently, she has started sending him pornographic clips. She is someone we both know very well. My husband told me about her and showed me her chats which is giving us serious concern. Although he has been too shocked to warn her about her misconduct but he has resolve to letting her husband know about everything. I don't know if this is a good idea or how can we handle this problem please?