is just the tip rape?

I didn't know at the time that that's what the guy who assaulted me did, but after my boyfriend teased me with just the head of his penis I have realized he put it in even though I told him not to. When I thought I felt it go in, I said "no", and he played dumb like he didn't do anything. 
I know he sexually assaulted me, but is that rape?
Edit: I am not looking to charge him. I have no contact with him because he blocked me. Plus I know there is not enough evidence to get him convicted of sexual assault.