is this assault?

in 8th grade my boyfriend at the time would let me come swim at his house during the summer. one day he had me go in the hot tub with him and he started to touch me under the water and i was okay with it so i touched him back then i left and went home and he texted me if tomorrow when we are swimming if he could just “slip it” in me. i told him no and i wasn’t ready for sex and that i just wanted to do what we did the last day but then next day i was sitting on his lap and we started to touch each other again when all of the sudden i felt a very sharp pain and i jumped off his lap. i felt really uncomfortable and actually went home early. i never really thought about it again until a friend recently asked me if i knew that my ex boyfriend stuck his dick in me. She’s friends with him and apparently he talks about it a lot. it makes me feel gross to know he did that but i don’t know what it is.. i feel uncomfortable. i asked my friend if that’s consider assault and she said that no and that i’m an attention whore for even just asking that. please help me. :/