TMZ has learned former UFC champ Tito Ortiz and baby mama/former porn star Jenna Jameson are withdrawing allegations that led to Tito's felony domestic violence arrest earlier this week.

Jenna, who accused Tito of injuring her during an argument, now tells TMZ, "What actually happened has now been dramatically distorted and misinterpreted and remarks that both Tito and I made after the police arrived reflect the state of shock that we were both in." Translation -- he didn't hurt me.

As for Tito, we're told he's now backing off what he strongly insinuated ... that Jenna is an OxyContin addict. We're told Tito's position now is that he found two OxyContin pills and may have jumped to conclusions. Jenna says the pills were very old. And, as we first reported, Jenna tested negative for drugs this week.

Tito's lawyer, Chip Matthews, tells TMZ the whole thing was "a big misunderstanding."