She dumped me, and she updates her relationship status with another guy the same day

So, when my ex broke up with me, she vaguely just said "things have not been the same anymore, and I have been going through a lot recently". She deleted me on facebook, and wouldn't really communicate with me at all. 2 weeks later, I'm on her facebook profile and I look at some of the guys liking her photos. I look at his profile, and see his relationship status. He is in a relationship with my ex, since the same exact day she broke it off with me, according to his facebook status. Now, I kept that to myself for a while. Couple of months go by, they break up. We start talking again. After a little argument, I lose my **** and tell her about how I know that she dumped me for this guy. First thing she says "no I didn't leave you for x wtf" To which I respond with the facebook evidence, and how she was in a relationship with him since the same exact date she broke it off with me. She then just says "Woah that's my personal life, and he cheated on me so I don't like talking about it" After I tell her that I would fully forgive her for everything, and how I apologised for snooping around her facebook, she just says "I can't do this anymore. I can't trust you. Sorry" So we said goodbye to eachother. Now my question: Is there a possibility that I was wrong about the fact that she dumped me for this other fella?

Yeah you could have been wrong about her dumping you for the other guy, but that shouldn't worry you because, going by your post, your ex is high maintenance and a woman who had little or no respect for you. If she did respect you, she wouldn't have broken up with you in such a vague way. Why bother forgiving her for anything, let alone everything, when there's nothing to forgive? It's not so much a matter of her not being able to trust you, it's a matter of you moving on and finding someone who's 'on your page' and someone who you can totally enjoy being with, without the dramas.