Denise Richards calls late ex-boyfriend Patrick Muldoon her 'best friend' in emotional tribute

Denise Richards is breaking her silence on the death of her ex-boyfriend, Patrick Muldoon.

In an emotional Instagram post, the 55-year-old actress paid tribute to her ex-boyfriend-turned-close friend of many years, writing that she is "deeply heartbroken & devastated" and finds it hard to put her feelings into words.

"You were my best friend & my family. We met in our first acting class, I was 19 never had an acting job and you were 21 a student at USC doing a recurring role on who’s the boss," she wrote. "And here we are. 36 years later. My whole adult life & I don’t know it without you."

Muldoon and Richards dated for nearly five years in the 1990s and remained close friends after breaking up. The two later worked together on the 1997 movie, "Starship Troopers."

PATRICK MULDOON, 'DAYS OF OUR LIVES' AND 'MELROSE PLACE' STAR, DEAD AT 57 AFTER SUDDEN HEART ATTACK

Looking back on their friendship, Richards wrote, "the friendship, love, support, respect & loyalty we had was unconditional and rare."

"You lit up every room you walked into. You are larger than life & Everyone was drawn to you," she shared. "So talented & most underrated actor. And most humble. Everything you did was infectious. Your laugh, your kindness, your wit, your strength, your loyalty, your passion, and your zest for life. We’ve been each other’s rock."

Richards went on to call Muldoon her "voice of reason & pillar of strength," saying he had had her "back and protected me more than anyone."

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"Especially during this last year of pain & heartache. And now I need you more than ever, for this pain and heartache losing you," she wrote. "Schweetbabe we’ve had those conversations.. We thought we’d live forever or at least into our 90’s. Schweetbabe I will be looking for those signs. I need to know you’re still here with me. I love you so much & miss you dearly schweetbabe."

Her post included a video slideshow featuring photos and videos of her and the "Days of Our Lives" actor together through the years.

Many stars sent Richards their well-wishes, including "Pioneer Woman" Ree Drummond, who wrote, "Your friendship was so perfect, pure, and sweet. So sorry, Denise."

Richards' daughters also sent their love, with Sammi writing, "such a beautiful video & message. love you so much" and Lola adding, "This is so beautiful mom, I am so so sorry. I love you so much, you guys are endgame forever."

Lola also shared her own tribute to the late actor on her Instagram, posting a photo of him and her mom inside a car, writing in part, "when i think of my mom i think of you," and that "life will never feel the same" without him.

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"I will really miss hearing my mom laugh on the phone with you. your voice always brightened my day and i’m gonna miss hearing it but i know my mom will more, but we will never stop talking about you," she wrote. "Thank you for being the best friend to her. thank you for being the one to make her laugh and forget about all she’s going through. that was a gift you had."

The "Days of Our Lives" star's manager confirmed the news to Variety. According to Deadline, Muldoon died on Sunday following a sudden heart attack. He was 57.