Monteith, who is now 30, previously entered rehab for drug abuse when he was 19.
Lea Michele, Monteith's off-screen girlfriend and Glee co-star told People (first to report the news) that she supports him seeking treatment. "I love and support Cory and will stand by him through this. I am grateful and proud he made this decision" (TV Guide).
A spokesperson for Fox says that Monteith's absence will not have any impact on production of Glee, which is currently still filming its fourth season. It has however, been confirmed that Finn (Moneith's character) will not be in the final two episodes of the season and his absence will be explained.
Well, Finn has recently discovered a love for teaching and the show mentioned him going to school for a teaching degree, so maybe that'll be it.
20th Century Fox also said in a statement that "Cory is a beloved member of the Glee family and we fully support his decision to seek treatment. Everyone at the show wishes him well and looks forward to his return" (TV Guide).
D'aw. I wish him the best.