mac: game freezes and crashes instantly

So the game worked great for me until I stopped playing for about two weeks because I had little free time. During that period, the home chef hustle pack came out. Then I had some time to play, and I loaded in my legacy save and almost exactly 5 minutes after opening the app, my sims were stuck in their idling animations, even when paused. I couldn't click on anything or save and had to force quit. this kept happening until today when it crashed as soon as I loaded the save. in this save my family is one elder, two adults, and four toddlers (yes they had quadruplets send help). but a few days ago when it was still crashing for around 5 minutes, I played a new save with just two young adults and it worked perfectly fine. I've tried removing my mods and cc but nothing has worked. Is this a problem with my legacy save file? I really don't want to lose these sims and their lives - I've been playing it since the first day I got the game. What else can I try?

My computer is a 3-year-old MacBook Air, and I tried playing with all other applications closed, but it still froze and crashed immediately. the most recent time, I used a mod to send my four toddlers to daycare, and I paused so I could click something for the elder. but after I paused, the toddlers were still moving towards the door. Again I couldn't click anything or save it, so I had to force quit again. Please help!

EDIT: I started a fresh game - moved my folder to the desktop - and added four toddlers to a new family. so far so good! does this mean I need to incrementally add in my mods and cc to find what's broken?