My brother keeps groping and pressing on me and i don’t know how to react

My brother keeps groping and pressing on me and i don’t know how to react

why is my brother doing this? I (f) have a brother (19m) and lately he’s been very touchy. a couple days ago, i asked him to crack my back. there were no sexual vibes until he fully cupped both my buttcheeks and i yelled and he apologized. and a few months ago he full on just gropped my tit and said it was an accident. today, i was in bed when he came and laid down next to me and i had a thick blanket on me but i could feel something hard pressing on me. i pretended not to notice and gave excuses thinking it was an accident but then he started pressing into my thigh a couple times then i asked him to leave which he delayed and when he got up i got see him adjusting his shorts. what does all this mean? i can add that when we were younger he used to rub on my ass but i didn’t know what it meant and blocked it out of my memory till recently. Any suggestions or explanations pls? also i got turned on and weirded out so am i in the wrong for this?