Demi Lovato just turned 23 on Thursday, Aug. 20, and she has received a bunch of birthday wishes from fans, family and friends.

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It is kind of surprising the sweet message Selena Gomez tweeted her though considering they haven't exactly been friends in recent years.

"I[']M so grateful you were born," Gomez tweeted Lovato, adding, "#nomatterwhat".

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She even included a heart emoji.

The two have a long history, having met in 2002 on the set of Barney & Friends.

They stayed close and even made YouTube videos together when YouTube became popular.

They starred together in Disney Channel's Princess Protection Program, which released in 2009 and they even recorded a duet for the TV movie's soundtrack called "One and the Same".

Then their friendship hit a rough bump in 2010 as Gomez became closer friends with Taylor Swift.

Lovato checked into rehab later that year and despite the shift in their relationship, Gomez still reached out to her. Then in 2011 they reunited, once Lovato was released from rehab, at the Teen Choice Awards and had a blast as seen in the photo above.

They have showed support for each other's musical projects since reconciling their friendship, but then they hit another rough patch just last year. Lovato unfollowed Gomez on Twitter over the summer.

Lovato went on record with Andy Cohen from Watch What Happens Live to reveal they were growing apart.

It seems like despite all of these ups and downs, deep down the two girls absolutely love each other and wish the best for each other.

Plus, Lovato recently followed Gomez on Instagram so perhaps these former friends are mending their friendship once again.

Tags: Demi Lovato Selena Gomez