Miley Cyrus Demi Lovato Twitter feud is heating up as the two former best friends unfollow each other on Twitter. How do they keep up with the Twitter feud if they can't read what each other is tweeting?

What started the feud brewing between former best friends Miley Cyrus and Demi Lovato remains a mystery. It goes back before Miley Cyrus MTV VMAs performance 2013 shot her to the top of the charts.

Demi Lovato and Miley Cyrus's feud seems to have started when Miley unfollowed Demi on Twitter. After seeing her Twitter followers go down by one Demi Lovato unfollowed Miley Cyrus and tweeted, "Ain't nobody got time fo dat!!! #pettybulls--- #toobusykillingit #cutethough #NEONLIGHTSTOUR."

Even before the Miley Cyrus Twitter war, Demi Lovato wasn't having the best week. Demis is about to split with the show "X Factor" and accidentally dropping an F-bomb during one live segment.

Demi Lovato has been talking about her eating disorder, self-mutilation, her battle with booze and drugs, and her BFF and fellow Disney star Miley Cyrus.Demi told the new issue of Seventeen magazine "[Miley] and I are strong headed. When we fight it's brutal and we're like, 'We're never going to be friends again!' Then two days later, were like, 'I love you and I miss you!'" 

So Miley Cyrus and Demi Lovato aren't exactly Twitter enemies? Where did the Miley Cyrus Demi Lovato Twitter war start? On Twitter, of course.Miley Cyrus has other BFFs besides Demi Lovato. One of them is Cheyne Thomas. Cheyne made fun of Demi's substance abuse problems. In December 2013, Thomas mocked Lovato's alcoholism in an Instagram video.

That re-ignited old feeling from a 2009 video Miley made that made fun of Demi and Selena Gomez.

The Miley Cyrus Demi Lovato Twitter feud gathered steam in 2009 after Lovato got snippy on a photo Miley posted of the two of them together with the caption "Now this is what true friendship looks like. None of that hollywood c***. @ddlovato I miss you :)"

Demi mocked the sentiments, tweeting "Yeah... It's just kind of hard to miss somebody that I don't know anymore."

Lovato tells Seventeen that she will always be friends with Miley, saying "Both [Miley and Selena] will never leave my life no matter what happens, because we've been through so much together."