Demi Lovato celebrates three years sober with Wilmer Valderrama

LOS ANGELES, March 16 (UPI) -- Demi Lovato celebrated her third year of sobriety Sunday.

The 22-year-old singer marked the milestone by sharing a photo of herself with boyfriend Wilmer Valderrama and captioning the picture with a sweet message to the 35-year-old actor.

"I wish I could put into words how grateful I am for this man right here," she wrote. "But my love has grown to a level that words could never possibly express how much this man completes me. He's loved me the way I never thought I deserved to be loved and with this day marking my 3rd year sober..."

"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," she continued. "I really wouldn't be alive today without him. I love you Wilmer."

Valderrama shared his own post, writing, "Today, we lay another stone together. 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.. I am proud and honor to be front row to see the world you are about to change. I love you Demi."

Lovato completed three months of treatment for bulimia and drug and alcohol abuse in 2010. She and Valderrama have been an on-and-off couple for over four years, and the singer previously credited the actor with helping her avoid a return to rehab for an eating disorder.