Caught a cheater

So I met this guy in tinder a while ago we had good conversation and we exchanged Snapchats. He never wanted to have a conversation after that, only wanted nudes. I asked him if he had a Facebook and he came up with him being hacked or some kind of bs. In his Snapchat username he had his last name. Me being the FBI agent I am, I searched him. What do I find? He has a fiancé and has been posting recently. ✨a liar✨ I took screenshots of the last conversation we had and he immediately unadded me. I don’t want him to get away with this but I don’t want to get lashed back because of it. Any advice?