If I understand correctly:
This was a week ago today and now nothing on this circuit will work!
that would seem to indicate that none of the wiring you did was "really messed up" because if so, the problems would have started as soon as you installed the fan. **Please confirm that the fan, light, receptacles ALL worked from "fan installation" until "this morning".
Assuming that is the case, there are a few possibilities:
- Something lose somewhere.
That can cause any number of different problems. The logical place, of course, would be any places that you recently worked on (i.e., the fan connections) but could be anywhere. Every wire should be connected with a secure wire nut or a screw. Check every box - fan, other lights (though depending on how the other lights are installed, that may not be so easy), receptacles, switches. If you find any loose wire nuts replace them. If you find any "taped only" connections, replace with wire nuts. If you find any "backstab" connections, replace with screw connections or, if no extra screw connections available (don't double-up wires on screws), add pigtail wire nut connections instead. Check (loosen and tighten if not 100% sure) every screw connection.
- A reverse or bad connection somewhere
The RT100 test showing hot/ground reverse is quite troubling. Hot/neutral reverse is common if someone simply gets black & white reversed when connecting to a receptacle. Hot/ground reverse should never happen as ground wire (= green or bare) is quite distinctive and the device connection (green or bare wire or green screw) is also quite distinctive. Check the tester in a receptacle on a different circuit - if it shows problems elsewhere then you either have "a big mess" or quite possible a bad tester. If it shows correctly elsewhere then that is another data point but it does not necessarily mean a simple "hot/ground reverse" as combinations of miswiring in multiple locations can result in almost anything being "diagnosed".
All that being said, yes, a miswire where the fan is connected could cause strange stuff elsewhere, particularly if unswitched hot is being passed through the fan (formerly light) junction box.
Try disconnecting (cap with wire nuts for safety) ALL wires in the fan box. Then see what does/doesn't work. You may well find that now some places that had power before have nothing now - including possibly the tester showing different results.
Beyond that, it depends on what you find. Anything more than two blacks and two whites in the fan box (except grounds, of course) is an indication that there is more going on here than a simple string of switched light fixtures. Pictures, as noted by others in comments, will help a lot.