My husband checks his ex FB page daily

My Husband checks his ex facebook page daily?
Ok I'm a little hurt to find that my husband checks his ex page eveyday. Ok it started by a friend emailing me to say my husband keeps sending her gf a friend request. They are exotic dancers and he did not know went to college together. She denied his request and he would send another. She also informed me that he has been invited and a part of these secret groups with sexual pictures and vidoes. I thanked her for the info then my mind started wondering and the distrust sunk in. I asked a friend if there was a way to see what he was up to. They told me how to check his account and I discovered how different his page looked from what I could see from my page. He had been liking sexual pics, sending dancers friend request and looking at his ex page every other day. He even looked her up while he was in the waiting room while I was having surgery. ..should I be concerned? I'm hurt but don't know how to address this.