"My love has grown to a level that words could never possibly express how much this man completes me," she wrote on Sunday, alongside a pic of the two kissing. " ... After sharing my ups, putting up with my downs and supporting my recovery... he still never takes credit and I want the world to know how incredible his soul is. I really wouldn't be alive today without him. I love you Wilmer."
Demi and Wilmer first got together in 2010, and reunited after splitting in 2011. Their relationship appears to be stronger than ever, with Wilmer also taking to Instagram to congratulate Demi on reaching such an important milestone. The former Disney star has been very open about her road to recovery, previously battling bulimia, cutting, bi-polar disorder and addiction.
"It is now 3 years since you said: I am more important than any past, demon, disorder or addiction. Where you decided that YOUR life was worth living while loving yourself. And I'm sure glad you did... I knew then the woman you've become now," Wilmer wrote. "I am proud and honor[ed] to be front row to see the world you are about to change. I love you Demi."