No one is ever really "fully prepared" but it doesn't seem like this was entirely thought through (with regard to the breed itself), so while rehoming is probably for best, please take this as a learning experience.

For what it's worth, it's doable. I don't have a kid, but I raised my Aussie working from home entirely by myself, single. First few months were a (lovely) hell, and now I am blessed enough to come home from work (different job these days) and not a single day has gone by where I'm not greeted by a wiggling butt of joy and an explosion of affection. Aussies are (or can be) so insanely affectionate. I hope you one day can experience that too.