my cousin is in love with my husband

yes you read that right. my cousin had messages on her phone that she would feel special if she could be with a guy like him. she also had commented to him that it was no fair that we had such a beautiful daughter. she has said things like how good looking he was and multiple other things. I never really thought anything of her Snapping him until I actually saw the messages she had sent. also she just spent last weekend here and she tried to play fight with him. she's barely 18. my husband and I have been together for 5+ years and are having baby #2....I know that he would never let that happen but wtf could be going through her head?! I chewed her butt about it. she thought it was 'family friendly conversation' sorry hunny I ain't buying it