My ex sexually assaulted me before ending the relationship

A little backstory, this was in the beginning of 2020. We were fighting more than usual, we were almost 4 years together, lived in our own apartment.

Before me and my ex really cut ties. The night before he moved out, the morning after. As I was waking up, he tells me. “I didn’t cum inside” I was so confused because I don’t remember anything from the night. Like I went to sleep and then woke up. I was like so shocked and asked what do you mean And he repeats “Yeah I didn’t cum inside you” Since things were weird already I kinda brushed it off. I’m a deep sleeper like he would sometimes go ahead and let himself on me and I would sometimes wake up mid way the sex.

Lately I’ve been thinking about it. Can I still report it? Is it too late?

How can I be sure he did?