Lea Michele and Cory Monteith
Lea Michele and Cory Monteith Twitter/msleamichele

American actress Lea Michele has spoken out for the first time since the sudden death of Glee co-star and boyfriend Cory Monteith.

The 26-year-old actress took to her Twitter page and thanked her fans for their support.

"Thank you all for helping me through this time with your enormous love & support. Cory will forever be in my heart," she tweeted, along with a photo of the two.

Monteith, who played heartthrob Finn Hudson in the hit Fox television series, was found dead in a room at the Fairmont Pacific Rim hotel in Vancouver, Canada. An autopsy revealed that he died of "mixed drug toxicity, involving heroin and alcohol."

Michele met Monteith on the set of Glee back in 2009 but their friendship blossomed into a relationship later.

Michele, who plays on-off girlfriend Rachel Berry in Glee, had talked about the couple's relationship in Marie Claire's Mexico's issue - one month before his tragic death.

"It's more interesting having a relationship with someone you work with because we get more attention because we play boyfriend and girlfriend on the show and we are also in real life. But he is the best person I know, he has made my life so incredible, and I am so thankful for him and not only to have him as a partner but also as a co-worker," she said, "It is important to have someone that supports you and encourage you, someone that makes you feel that you are unstoppable, that you can do anything in the world because you have him."