Wilmer Valderrama is ''completely devastated'' by his ex-girlfriend Demi Lovato's suspected overdose.

The 38-year-old actor - who dated the 'Cool For the Summer' hitmaker from 2010 until 2016 but has remained friendly with her despite the demise of their relationship - didn't realise how bad the 25-year-old singer's ''issues'' were until he found out she had been rushed to hospital on Tuesday (24.07.18).

A source told Us Magazine: ''Wilmer is completely devastated and he still loves Demi and it was just a matter of scheduling and time that they needed to make a romantic relationship work.

''He was not aware that her issues were this severe and intense at this time.

''She's been honest with him about her relapse, as she has with her family, friends, fans and the entire public, especially with her new song ['Sober'], but he didn't think it was this severe and that she would be struggling so much and have a situation that had these repercussions.

''Her friends and him are just hoping that she gets better and that she can be great and thrive.''

Demi was found unconscious at her home in Hollywood yesterday by two of her friends and, although it's not yet known what she had taken, her life was reportedly saved when one of her pals administered a Narcan shot - medication used to block the effects of opioids - she had on hand.

An insider explained: ''One of her friends had Narcan on hand in case something like this happened. Her friends knew this was coming because she's been using so much again. They were up all night partying the night before at her house. Luckily, the Narcan worked and she will recover.''

Demi - who has battled with addiction in the past - had been clean for six years but candidly confessed to a lapse in her sobriety in her recently-released track 'Sober'.

Lyrics to the song featured her apologising to her friends, family and fans for hitting the bottle again.

The brunette beauty is currently recuperating in hospital surrounded by her loved ones.