My bf and I met through a dating app and started dating in December 2020. I was completely invested in the relationship and had clearly conveyed it to him that I was looking for something serious. He also made it clear that I was the only person he was seeing at the time. He proposed to me in early July 2021. After 6 months of the relationship I found out that he was actually seeing and sleeping with multiple girls when we were dating. I decided to forgive and move on because all these lies were in past. Recently I saw steamy pictures of him with one of those girls on his phone. Some of them were from 15 days before he proposed me. I am heartbroken because I emotionally invested on him but he was doing all this behind my back. Even worse, he still has those pictures. When I confronted him, he was neutral about it and hasn't even apologized yet. He is pretending like it was not a big deal. I dont know if I am over reacting or how to forgive him for this and move on.