Oooh. I just got caught up but I like the potential here. There is definitely an interesting story where Clara starts to spiral a bit into regression with Stacy's help and has a great time being a big baby.
Though I can see how if you go the route where she is more okay with it you might want to just delete the bit from the future at the start of the story. It is such a clean cut from that to the next chapter, and the rest of the story is strong enough, that you could do that anyway if you feel it helps make it easier to write.
Though paused right here you definitely have a lot of options for turning the story back towards your initial goal if you think that is more interesting. Like the emergency course correction option is still available where Clara could for once manage to find the right words and explain to Stacy that she has misunderstood things a bit.
I think after that idea she has planted in Clara's head it would be funny if Clara managed to explain to her that she isn't usually such a baby and would like Stacy's help to get her back to normal. Then they could end up switching sides with Stacy trying her hardest to undo what she has started while Clara is just falling apart after all that has happened and is using regression to cope more and more.