Like a scene from a movie

So I have been in the long distance relationship for almost 8 years and today an unknown woman sent me a message saying she has been his girlfriend for 2 years and that they live in the same city and planning to get married, that she told him a few times that he should end this with me. All the conversations we had over apps are gone, no trace. In the past months at least this is what he told me he was depressed because of his family and things that happened at work, he got fired. I gave him my support the best way I knew, but also a space because you should not push person too hard when he is fighting depression. We contiued texting and talking but not as often as before. She, texted and said non of this was truth and that I was basically fullish for trusting someone who is far away, that she read all the messages.. I am completely shocked. When you are in the LDR you have this scenario at the back of your head, but never thought it would happen to me. We were talking about getting married, building a house.. I trusted him.. I want to belive this woman is just some stupid joke, but..