The singer and a big group of friends hit up Barton G in WeHo Tuesday night for dinner. As they left, Demi struck a chic pose with her buds to commemorate the occasion, no doubt a pivotal moment for the singer.

It was exactly a year ago Wednesday when Demi -- who struggled with addiction for years -- was rushed to the hospital following her near-fatal overdose. She'd been sober for 6 years before relapsing but has made it priority No. 1 to live a sober life again.

Demi's surrounded herself with a strong support system. In fact ... her team back in January surprised her with a slice of cake to celebrate 6 months of sobriety with a note that read in part, "We are so f**king proud of you!!"