Help!

My husband and I have been together over 20 years since I was 13 and he was 16.We have been married since 2011.We have had the same group of friends that are still are friends.One I would consider my husband best friends and one of the sweetest men I know.Recently he started texting me at first it was fine like how are you and just asking questions telling me how pretty I am in pics on ig.Then he told me he has always liked me thinks I am so sexy.I thanked him and reminded him we are both married I adore his wife.He kept on messaging me on Instagram to the point I deleted it.Now he is texting me again sexual stuff.I keep telling him stop but he is like no I can’t help myself.I won’t tell a sole because I know somehow my husband may blame me it could destroy friendships all of the above nothing good from this.😭