Jax Taylor says he didn't want to go to rehab ... but, once he was in, he never wanted to leave -- because it gave his life crucial structure.

The reality television star posted a clip from Friday's episode of the "When Reality Hits with Brittany and Jax" podcast ... admitting he was super scared to get, clean originally hating the whole experience.

After a few days though, JT says his mindset changed -- and, by the end he worried about going back to the world outside rehab ... bawling his eyes out when it was finally time.

The way Jax tells it ... he had a set schedule -- getting up in the morning, chowing down on breakfast, reading. Basically, Jax enjoyed the structrue, and he worried about his life outside of it.

Plus, he says he knew everyone outside those walls would be pissed at him for his actions -- and, he wasn't ready to get back to filming his show, "The Valley."

Obviously, Taylor did come back to society ... and, it's been a rough few weeks -- with the star looking pretty down while filming the show with his ex, Brittany Cartwright recently.

Plus, Brittany filed for divorce a couple weeks ago ... officially pulling the plug on their five-year marriage. Bascially, it hasn't been easy for Jax since getting out of in-patient treatment.

The storyline of their split's set to play out on "The Valley" season 2 ... and, we're sure to hear more of Jax's time in rehab.