Underwood, who is the father of the MTV star’s daughter Sophia, died in 2008 — one month before Sophia was born. Underwood was the driver in a fatal car crash that killed another teen and injured a third.
Sharing a montage of photos marking their time together, the former Teen Mom star, 27, paid tribute to their time together.
“You gave me that once in a lifetime love of my life everyone so deserves, you gave me so many 1st’s, from virginity, proms, trips, my first ring, you showed me unconditional love, you showed me what relationships are, from prom, graduation, to our only child,” she wrote in an emotional post to Instagram.
The post featured several photos of the pair in high school, including loving Myspace messages that Underwood sent Abraham before the car accident that would take his life—eight months into her pregnancy. Last December marked the 10-year anniversary of Underwood’s death.
The post also includes a video of Abraham flipping through a photo album with Sophia, 10. “Oh my gosh, Daddy Derek’s favorite person,” Abraham says, pointing out a photo of the high school sweethearts.
“All the events that had happened the entire sequence was one filled with the thrill, love & loss. Now I share a birthday breakfast in your memory & all our best photos and your childhood photos with our daughter,” the reality star’s post continued.
“I see all of your messages to me, & your written letters. Thank you for being the best loving man I know, and one of the strongest. All the memories we had. Our groups of friends & haters can’t deny our legendary times, from school, parties, summer nights & in-between.”
The caption concluded: “My partner in crime getting me in all the trouble – love you legend we all miss you today more then ever & so much love, memories from Sophia & I , family, friends and those who watched over the years , Happy Birthday I love & miss you, and thank you for everything you did for me❤️🎂 ( these pictures & video of sophia today made my May so blessed ).”
Tributes to Underwood were also shared on Sophia’s Instagram, which is managed by Abraham.
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“Today is my daddy Derek’s birthday! I’m sharing some little memories with all of you guys today,” the caption says. “I’m so thankful for my mom being there for me in my hardest time when I think about my dad and I miss him so so so much.”
Sophia’s post features several of the same photos as her mom’s, as well as the same video.
Back in January, Abraham shared a 10-year challenge photo with her daughter, saying she’s “truly the luckiest” to be Sophia’s mom.
“I have Known this amazing, wonderful , smart , talented, beautiful & God loving child for 10 years. @sophialabraham has helped me be the best me,” she said.
Although Abraham and Underwood weren’t on good terms at the time of his accident, Abraham shared in her book My Teenage Dream Ended that he was “my first love, my only true love.”
She also told Bethenny Frankel in 2013 that she would have married Underwood if he survived. “I probably wouldn’t be where I am if I had that life,” she said.