In legal papers, obtained by TMZ, Christina says despite what Ant has said, she sees their 2-year-old son much more than "9 full days each month." Christina also has an issue with the fact Ant believes she has essentially used their son for social media clout and sponsored posts.

Christina writes in her declaration, "I have never once commercialized, been paid to use, or used Hudson as a prop or a promotional tool for any television program or product." In fact, Christina claims, Ant's the one who uses Hudson for commercial gain ... she also includes some example posts from Ant to help support her point.

Christina also mentions Ant's concern she ingested hallucinogenic toad venom as an attempt, "to smear my good name and tarnish my image."

As for the COVID situation, where Ant says Christina returned Hudson to his care after her entire family had exposed the two-year-old to the disease ... Christina says she was the only person who actually had COVID, and was asymptomatic.

She tells the court there's no need for an emergency order to grant Ant full custody of Hudson ... and so far, the judge has agreed.

TMZ broke the story ... Anstead went OFF on Christina in docs filed Thursday -- accusing her of being an absent mother, putting Hudson at risk and not providing for him in necessary ways.

He also pointed to an example of Christina driving Hudson in a golf cart without a seatbelt as an example of her reckless behavior ... but Christina submitted a pic of Hudson wearing one around his waist.

At the time, Christina told us, "What Ant is doing deeply saddens me. If this was really about Hudson, as he says, this should have been handled privately with a private judge or mediation, as myself and my attorney have suggested. I have had my share of ups and downs but I am a good mom and I love my children with all my heart and I will always protect them."