04/22/2013 at 08:00 AM EDT
has nothing but pride in her heart for her Glee
costar Cory Monteith
, who is currently in rehab
for substance addiction.
"He's such an amazing person, and it takes a lot to be able to admit that you have a problem and then seek help," Rivera, 26, told PEOPLE at the GLAAD Media Awards in Los Angeles on Saturday.
Rivera adds the Glee
cast has rallied around Monteith's girlfriend
, Lea Michele
, saying they are close-knit
and look out for another in both good times and bad.
"We're all one big family, and he's a member of our family so we want to see him better," said Rivera, who plays Santana Lopez on the Fox show
, now in its fifth season.
The show's creator, Ryan Murphy, has also publicly voiced his support for Monteith, 30.
"I am so proud of Cory Monteith and love and support him 100 [percent]," Murphy Tweeted
on April 1.