I feel your pain. I have been following your progress/setbacks with your Rock Star Sim, and I don't blame you for being upset. I don't use the RTF mod you are using but my game is also a glitchy mess even when I play a vanilla save file. I remember your hubby bought that PC for you as an anniversary gift. And maybe my memory is way off, but that wasn't all that long ago. So the fault here is with Island Living itself because there are many Simmers complaining about random crashes. I am playing the game on a six month old gaming PC yet I am having more problems while playing Island Living on my desktop than I do while playing it on my laptop. Which doesn't make much sense to me. I went so far as to uninstall Sims4 after backing up the important game files, then did a fresh installation. Doing that did get rid of a few smaller glitches. After repairing your game do you restart your PC? I have found restarting your PC after repairing helps. Don't understand why, but it does help. The other concern I have is this is happening with the same Sim. Do the crashes happen during a certain interaction, event, or while certain Sims are on the lot? When City Living was released I lost an older save because it became corrupted for some unknown reason. I had just two mods in my game back then and didn't play until those were updated. Island Living has impacted a lot of the features from past packs. Do you use the UI Cheats Extensions mod? I have been using it along with MCCC for a couple of years. I use it mainly to cancel out those bothersome moodlets so my Sims don't die because they're too happy, or too playful, etc. I also hate seeing their facial expressions change every few seconds. LOL
Hang in there. I am trying to sort through a long list of bugs myself and I know how frustrating it is. Hopefully the devs will have a hot fix patch for us later this week. :)