My friend bitched about me on twitter?

Ok so i was really upset about this yesterday and still am. Me and my friend laura are like best friends, I completely trusted her. So I was upset about something that happened a couple of days ago, where i thought she lied to me and went off with her friend jane. I explained to her how I felt when we were chatting on facebook, because I thought well were best friends so I should just say it to her. And she explained what happened and I was like Its okay . So then she said she had to get off the laptop and I said bye . That was over with, I though all was cool. So than I was randomly on twitter going through peoples profiles ad found lauras. She had started bitching about me literally a second after she logged off facebook, and i saw it all! I am so upset and I feel like my friend betrayed me.Me and her had a private convo and she just went and told jane. I can never trust her again. Should I tell her I saw it all on twitter? Even if she did apologise i dunno if i could ever trust her again. Why did she do this??????