Denise Richards Honors Late Ex Patrick Muldoon on His 58th Birthday

Denise Richards marked what would have been her late ex-boyfriend Patrick Muldoon's 58th birthday with a touching tribute on Instagram Sunday, five months after his passing.

Richards, 55, shared a series of photos of the actor, including one of them on a runway beside an aircraft. "This was our last hug saying goodbye..... if only I hugged you tighter and longer," she wrote. "We had just gotten off our flight from Scotland.. a whirlwind weekend with our Starship Troopers family."

Muldoon died on April 19 at his home in Beverly Hills, California, from a heart attack. He was 57.

Richards, known for her roles in "The World Is Not Enough" and "Wild Things," recalled Muldoon as "always so humble" during their last encounters. "We hung out in the lounge waiting for luggage talking about what a fun weekend we all had, I haven't laughed that hard in a long time," she said. "We talked about plans of getting together & gave each other a hug and that was the last time."

Richards and Muldoon, who co-starred in the 1997 film "Starship Troopers," were in a relationship for over four years in the 1990s and remained friends afterward.

She described the day as difficult, stating, "I know you know, how hard it is for all of us. It's taken me all day to even post this... this is hard."

Richards shared that she continues to feel Muldoon's presence since his death. "I feel you and see all your signs," she wrote. "Well I'm sure not all because these big ones show up, I laugh out loud hearing you say 'Schweetbabe how do you not see what I've been putting in front of you?!? Now do you get it?'"

She also remembered Muldoon's connection with her daughter Eloise, 15. "A year ago today we were at the LA comic con and Eloise wouldn't leave your side... you had her giggling all day," Richards recalled. "She loved helping and watching you while you signed pictures and had everyone laughing. She was so happy being by you. She lit up today when I told her it's your bday and when I reminded her of last year she started laughing thinking about you."

Richards expressed gratitude for their time together, particularly a recent trip to Scotland where they spoke for hours. "What a blessing and gift you gave me," she wrote. "Happy Birthday... as we would say... I miss you dearly & I dearly miss you Schweetbabe."

The pair also appeared together in the film "Dirty Hands," released digitally on April 24, shortly after Muldoon's death.