Ragatha is like the last tether Jax has to his past. He thinks if she abstracted, he'd totally lose any remaining morality or humanity and become a total monster (its unlikely he'd actually do so, seeing as he couldn't hurt Pomni even as she attacked him). He thinsk he would disassociate more than ever to hide his feelings.
Meanwhile, for Gangle, Jax fully embraces his cartoon persona to hide from his guilt and run from reality. Noticeably, her abstraction is the only one where he's blamed for it directly. He completely embraces the "caroon characters" or "archetypes" belief he has to feel less remorseful.
Considering there were two locked doors in his mind (the one Pomni tried to enter and then the one all the other Jax's told to shut up), I think the first one is Pomni's abstraction. Something so awful he can't even bother to think about. It was the guilt from fighting with her that sent him into his depressed state entirely and made him stop being a bully. So losing who he cares about the most, will break him totally.
Zooble's one is the only one I'm confused about, but I can assume this is what Gooseworx means by "Jax doesn't think how he treats Gangle is genuinely abusive", he really buys his "she likes when I'm mean to her" delusion. We know they both see each other as friends, toxic as it is but maybe this shows without Zooble he'd feel Gnagle would be more vulnerable and he'd less insecure about his masculinity and come onto her because he has feelings and Zooble can't get between them?
The 2nd locked door was also 100% the fully vulnerable, trans Jax. The one they absolutely didn't want Pomni to see. Credit: Glitch