Jax Taylor considers his son to be his "biggest accomplishment" in life.

The 45-year-old reality star has taken to social media to celebrate his son's third birthday, explaining that Cruz makes him want to be a "better person".

Alongside a series of throwback photos, Jax - who has Cruz with his estranged wife Brittany Cartwright - wrote on Instagram: "I've made a lot of mistakes but you are by far my biggest accomplishment son nothing in life makes me happier and want to be better person for you.

"You are the best thing that has ever happened to your mother and I. We love you to the moon Cruzy. [heart and dinosaur emojis] (sic)"

Brittany, 35, filed for a divorce earlier this year. The reality TV star requested primary legal and physical custody of their son, and a source subsequently suggested that she felt the move was in the best interests of Cruz.

The insider explained to PEOPLE at the time: "This step has been a long time coming and something Brittany knew she had to do for the best interest of herself and her son in order to move forward and put a stop to this tumultuous cycle they've been living in.

"Jax is feeling mixed emotions. He knows this is ultimately the right decision but is sad that things ended up the way they have. It's an emotional month for him and he's trying to stay strong for his son."

Jax and Brittany tied the knot back in 2019, but they're both determined to maintain a good co-parenting relationship.

The source added: "Their main priority is getting to a place of being amicable co-parents for their son."