How 'Teen Wolf' 's Tyler Posey Is Moving on After Losing Mom to Cancer and Ending His Engagement

Tyler Posey will be the first to admit that he’s had an “awful” year.

A little more than 12 months have passed since the Teen Wolf star’s mother died, a personal blow only worsened by the fact that it occurred mere months after his engagement to his childhood sweetheart ended.

“This has been the hardest year of my life,” Posey, 24, says in the latest issue of PEOPLE.

Posey had proposed to girlfriend Seana Gorlick in 2013 after a decade of being “in love,” but the engagement had ended (under circumstances Posey prefers to keep private) by October 2014.

“I still really miss her,” he says of Gorlick. “I can’t believe I have an ex-fiancée.”

But losing his mother – who died at age 55 last December after a four-year battle with breast cancer – proved even more devastating.

“She was my best friend,” Posey says of his mom, Cyndi, who had homeschooled him and served as his business manager when he was a child star filming movies like Maid in Manhattan. “She was the glue that held our family together.”

Posey says he is still close with his father, character actor John Posey, 60, and brother Jesse, 21, but “I’ve lost my sense of family,” he confesses.

And suffering through those losses led the Teen Wolf star to a struggle with depression.

“Whenever I have too much downtime, I start to get sad,” he says.

• For more from Posey, including how he’s moving on after a difficult year, pick up the latest issue of PEOPLE, on stands Friday

So, Posey has thrown himself into his work.

The actor and host, who also dabbles in music, became a producer at the beginning of his MTV show’s current fifth season. And he’s slated to direct an episode during season 6.

“Keeping busy keeps me sane,” he says. “I want to put everything in my career.”

This past year “has really changed me,” says Posey. “But I like who I’ve become. I’m growing every single day. After everything I’ve been through, I’ve realized I can do anything I put my mind to. And I want to do it all.”

Teen Wolf airs Tuesdays (at 9 p.m. ET) on MTV.