Need your opinion please!

My husband has always been a great listener. It’s one of his greatest traits. He has a friend who’s he met about a year in a half ago, they share the same hobbies and that friend has gone through major marital issues and my husband has lent him an open ear. Well, my husband just received this message from him yesterday and you know, anytime a text that begins with “don’t let your wife see this texts” it’s never good. My husband showed me and I showed that I was very uncomfortable of what was said. My husband brushed it off and said he’s just joking and to take it with a grain of salt. What would you think of it if you were in my shoes? Of course, I’m not going to do or say anything but I do feel a little weird inside at the fact that we let this individual into our lives and treated him like a brother. Just not quite sure how to feel or if it is in fact harmless. Please share me your thoughts!

(My husband in blue, friend is gray)