Thank you again for your continued, well-thought-out advice! It does mean a lot that you're willing to put in this time and energy for a stranger.
Unfortunately on my end, I got my answer. Yesterday morning (before I even received your response, actually) I reached out asking if we could have a conversation about the breakup and how we would like to define things henceforth. They never texted back. And after a year of dating them, I know my ex well enough to know that a lack of response is a full answer in of itself.
Honestly, my hopes of continuing the relationship, or even building a friendship, was based on the uncertainty I had about how they felt about me now. Now that my uncertainties have been answered, I can move on. It hurt, yeah, but it's also relieving to finally be walking away from all the stress and second-guessing. Plus I have so many friends who have been wonderful, constant support through all of this, and I am happy to spend my life with all of the people who have proven to me multiple times that they will always be there for me.
I think I'm going to leave this thread up, in case anyone else comes by dealing with a similar situation. And like you said, it does all come down to communication. Hopefully if an allo and an aro realize they're in a similar situation that my partner and I found themselves in, they can learn from this how to maturely address it, instead of it turning into a whole messy process like it did for me.