It is easy to get discouraged and almost as easy to just give up. Nothing wrong with that, per se, if you have a different career to fall back on or wish to pursue. As you are experiencing, hiring is slow, even at the Part 135 shops.

Even if you think going back to instructing would not show "progression", it is still a flying job and allowing you to build hours and maintain a certain level of recency. That is perfectly fine to do. My 2¢ would be to instruct while also hunting for a part 135 opportunity. Hopefully one will present itself which could get you back on your feet and headed in the proper direction. Not all is lost here but it certainly will be a humbling, uphill climb.

*Added bonus would be getting on with a flight school that has a twin in which you could obtain your MEL (if you do not have that) and build multi-time. Plus-Plus bonus if that school can help you get your ATP in said twin to help you get hired somewhere.