How can I forget this ever happened? Should I tell?

last night I went into my sisters room to find my phone back cuz she hid it somewhere. it was around 9 and she was gone so i didnt think much of it when i searched in my tshirt and briefs (was going to bed) when out of nowhere i heard her and 2 of her friends about to come up the stairs. i couldnt believe it, she just left and was suppose to sleepover at her friends instead they ended up coming here. so i froze and didnt want to run out cuz then theyd see me. senses finally came and i hid under her bed. i heard them come in and could see their feet. my sis is really tall like our parents at almost 14 shes already 5'10"/118lbs, when im short thanks to my aunts and grandmas at 4'8"/77lb just turned 17 (embarring) so after like 2 min out of nowhere something vibrates really loud right next to me, yep my phone. my sis and her friends heard it cuz then my sister came down to floor and couldnt believe i was under her bed. she laughed so loud and told her friends about me, they laughed to then and wanted me to come out. but i didnt want to cuz i swear i almost never wear "tightiewhities" but my sis didnt care and wanted to embarr me so bad. she pulled me by my feet so they could see my . i was so humiliated and tried running out but my sis blocked the door. she picked me up and carried me to her bed. i hate it when she sits me on her lap she's lucky she outweighs me. she asked me if i was looking for my phone then joked that i might as well wear little girl undies making her friends laugh more. i begged her to just let me go but she said since i snuck into her room, she had to punish me somehow. i told her that shes insane and again to just let me go but she wouldnt. she had her friend get one of her old pink barbie underwear and put them on over my underwear. it was so humiliating cuz they fit me and they all thought it was so cute. then she sat me on her lap again and so this time i stomped her foot which was a mistake cuz now she was mad and took it way too far. she had her friends hold me down on her lap while she ed me for like 3min really hard. then she let me go and i ran into my room. i still feel so embarred that this happened and havent even told my mom yet cuz im so hurt. How can I forget this ever happened? and should I tell on my sister?