Is it sexual assault??

So there was this guy I was in a relationship with and I went to go visit him for a sleepover I didn’t really think much was going to happen that night since the relationship was still pretty new but unfortunately something did happen we were just sitting on the bed and we started kissing and it led to other things to him taking my pants off and trying to have sex with me which is something I wasn’t sure of I didn’t even know if I wanted to do it but he was already on top of me and I begged him to stop I told him I don’t want to do this anymore I started crying trying to push him off me but it didn’t help he just continued while I was crying and he finally got off me and just slept while I cried throughout the rest of the night and I wasn’t really sure how to feel , I continued with the relationship don’t judge me I know and I somehow managed to suppress that memory but sometimes I would ask him why he did what he did and the answer was always I’m trying to ruin his day but eventually the memory resurfaced again once I broke up with him and I don’t really know how to deal with it, it feels like I am reliving it once again and I just keep beating myself up for not breaking up with him soon , for even just interacting with him I hate him and I hate what he did to me I hate feeling like this like there could have been something else I should have done to prevent it from happening