>>281491993 (OP)
You shimmy backwards so her hips are on your back so you have room/leverage to tuck your knees in and get a base to stand up. If she doesn't react you can just slip out backwards. If she does react, you can lean back and walk yourself up while bracing against her. Meanwhile, grab her wrists and push them down so she can't circle your torso with them. Once you're relatively stable and you've broken her grip, spin 180 as fast as you can to complete the escape and return to a neutral standing position.
If she's trained, you're still pretty fucked due to the weight difference but otherwise you have a great shot with this gameplan. Good luck chickening out of your giant dommy mommy fetish.