a lot of autistic people struggle with feeling empathy towards others at certain times just because it’s “too much” and often not comprehensible what you’re supposed to do, or why they’re crying. that’s pretty normal! i experience that as well.

as for c-PTSD, it could be due to someone crying stirring something up for you that you dissociate from, causing you to feel numb.

I am Autistic and struggle with empathy and i have experienced this but i don't Always struggle with empathy

Both of adv3nture’s comments are things I was thinking. Plus, depression literally saps you of energy. It could be any one of those—or a mix of them—in different situations. I’m not sure if this is the kind of answer you’d want, but IMO, it’s best to let your mind do what it needs to do at the time, even if that means feeling numb. You can always come back to the event in later conversations when your brain is able to tolerate it.

I have the same problem, I dont know how to handle other people's emotions. I freeze up in the moment and I always feel awful, but my mind goes completely blank when that happens. Like others have said, It's probably a mix between the autism, cptsd, and depression. It's okay to struggle with empathy, so many neurodivergent people do. The best you can do is address it at an appropriate time with the other person, and brainstorm ways to help them in those moments. It's easier to have a script than to figure it out in the heat of the moment.