This guy that I had a little fling with about 10ish year's ago, we never had sex but we fooled around for a month or so found my Instagram, and started messaging me being super flirty, telling me how much he liked my body and how he still bought of me all time. After telling him I wasn't interested in anything or even talking to him that I was in a serious relationship and was getting married. He told me he had a girlfriend who he has been with for 3 years and then asks me for a super-secret picture since he never got one when we were talking. I feel like I should reach out to the girlfriend and tell her what a scummy gremlin of a boy she is with. But also know this guy has issues and am a little worried that if i say anything he might show up randomly and cause issues. Any advice on what i should do?