Denise Richards is paying tribute to ex-boyfriend and frequent costar Patrick Muldoon, who died Sunday at age 57. She wrote: "This is so hard for me to put into words. I am deeply heartbroken & devastated losing you. 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. And here we are. 36 years later. My whole adult life & I don’t know it without you. 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. 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. Our memories together are endless. You’ve had my back and protected me more than anyone. I don’t know what I’m going to...