Should I rat out my ex for cheating on his current girlfriend with me?

I just had with my ex after he told me he was seeing someone casually. I understand that we live in different states but he says he still has feelings for me and I do for him. I was seeing someone but was single when I hooked up with him. I go online and see photos of the 2 of them together. It is not casual at all. She is completely enamoured by him, is moving in with him, but the worst thing is, she has a child and he is in dire financial straits. The worst thing for me is that fact that he had with me this last time and never even called me back! I feel used and betrayed. I ended up contacting her and telling her everything about his slimy ways. He totally discredited me by saying I was crazy and was just angry for him dumping me months and months ago. She took the photos down of the 2 of them for 2 days and then put them back up today. I dont feel loyalty to him at all, I just answered all of her questions. Now I feel like the loser.