Jason Priestley is 'in so much pain' after losing dear friend Luke Perry

There's no timetable to grieve the loss of a loved one; you just do the best you can and try to cherish that person's memory.

And that's exactly what Luke Perry's "Beverly Hills, 90210" co-star and friend Jason Priestley is doing.

The actor took to Instagram overnight and wrote a heartfelt note about Perry, who died at 52 years old on Monday after suffering a massive stroke the week prior.

"It's taken me a couple of days to figure out how to write this," he began. "My dear friend of 29 years, Luke Perry, was one of those truly special people who really cared... Luke was not only a star, he was an incredibly bright light that was extinguished far too soon... and that is why I, and so many others, are in so much pain today."

The 49-year-old actor added that if you ever met Perry or became friends with the man, he knows "you are sad today as well."

"The candle that burns twice as bright only burns for half as long... you burned oh, so brightly Luke... Goodnight Sweet Prince," he closed his heartfelt note.

Priestley hasn't been the only "90210" co-star to speak out about how "devastated" they are by the sudden loss.

Shannen Doherty: "A phone call that devastated me."

His love interest on the show, Shannen Doherty, also posted earlier this week about how hard it is to accept the loss of such a close friend and co-worker.

"Yesterday morning I got a phone call that devastated me. I'm struggling with this loss and am having a hard time with my thoughts. But, my heart goes out to his family and friends who were blessed by his light in their (and mine) lives. Processing this is impossible right now," she wrote, accompanied by photos from their time on the show together.

The actress expounded to People magazine, saying, "Luke was a smart, quiet, humble and complex man with a heart of gold and never-ending well of integrity and love. Luke reached out to me during my cancer journey and we picked right back up, albeit older and wiser, but that connection remained in tact," she added. "I will miss him everyday. Every minute. Every second."

Ian Ziering: "God please give him a seat close to to you."

Another heart-wrenching post came from "90210" star Ian Ziering. His letter was a direct tribute to Perry.

"Dearest Luke, I will forever bask in the loving memories we've shared over the last thirty years," he wrote. "May your journey forward be enriched by the magnificent souls who have passed before you, just like you have done here for those you leave behind. God please give him a seat close to to you, he deserves it."

Gabrielle Carteris: "Luke was a tremendous force."

"I am absolutely heartbroken," Gabrielle Carteris, who played Andrea Zuckerman on the '90s show said in a statement. "Luke was a tremendous force in the lives of so many. He was a very sensitive soul who was kind, generous and he fought for the underdog. He was a strong voice and an advocate who will be so missed by all who knew him. He has left his mark -- never to be forgotten. My heart goes out to his family, friends and fans around the globe."

She later tweeted more about her former co-star.

So many others: "I'm in utter shock and heartbroken."

Fellow castmate Tori Spelling, who played Donna Martin, also spoke to People, saying, "I'm in utter shock and heartbroken. I'm saddened for his kids whom he adored beyond words. He was so proud of Jack and Sophie. Luke was one of the kindest and most humble human beings I've ever known. I'm grateful for the years of friendship we had. He truly was family to me, a protector and a brother. I'm so sorry for the loss that everyone is experiencing."

"My heart is broken. He meant so much to so many. Such a very special person," Jennie Garth told People. Garth played Kelly Taylor on "90210," whose character had a relationship with Perry's Dylan McKay. "I share my deep sadness with his family and all who loved him. Such a terrible loss."

Christine Elise McCarthy, who starred in an early season of "90210" as Emily Valentine, also shared her thoughts.

"With the heaviest of hearts, I am stunned and devastated to tell you that Luke passed away. I am still in shock and I have no words beyond saying he was a truly kind gentleman. He will be mourned and missed by everyone who knew him and the millions who love him," she wrote. "Your time here was far too short."