Here's the situation: I'm playing a legacy and my third gen heir just moved off to college. When I went back to the legacy house, the game crashed! I've tried the hood without CC. I've tried ripping a copy of the lot out of the hood, using the Lot Compressor, then moving them into that version. I've moved them into a different house, and they were fine. I'm just not willing to give up the house, though! It's ugly, but I made it and I'm attached

Is there really no hope? I haven't made backups of the hood, and this is because of my hubris, so now I either have to give it up or somehow fix it. (don't worry, though, i made backups before all of the fiddling i mentioned earlier, i'm not that dumb.)

What to do if/when next time. Some of this you can't do now.
1) Make sure any house you want to keep intact has a stay all shrub. (must have a sim click the shrub) Just in case you ever do have to move sims out.
This is from Simlogical.
2) Make a back up.
3) Run hood Checker.

4) If the lot won't load after running hood checker then move the sims out. Make sure they are all working fine on another lot.
5) Clean the lot with the compressor now as this should only be used on empty houses. (no living or dead sims)
6) Try loading it again. If it loads click the lot cleaner globe save and exit to hood, reload and move an item, save again.
7) If the lot is empty of sims, has had sim reverences removed and had the lot cleaner globe used on it and it still crashes you are out of luck. But make sure to do all 3, hood checker, lot compressor and globe cleaner.

I have a few graves on there that I wasn't able to rescue, so I still don't think I can use the compressor, sadly. I had ran hoodchecker and forgot to say, so I think I'm all out of options here. Either way, thanks for the help! Maybe this will give me the chance to make a less ugly house that fits with the rest of my neighborhood better.

You could try finding the lot in the lot catalog folder and moving it into an empty hood and trying the cleaning and debugging on it there.
If you rebuild save the lot to file before moving in sims.