Uhhhhh what do i tell my friend??!??!?

so my friend and i were in my room watching jersey shores (oh yaaa i LOVE that show) lmfaoo anyway shes bi and she was laying next to me she kept touching my breasts and stuff and i didnt say anything i just kept looking at the tv. then she put her hand up my shirt and kept messing around with my breasts and i like froze. i wanted to say sompthing but couldnt i just sat there. she kept doing that then stoped because my mom walked in. then later at around 12:00 pm we were going to bed i sleep on my back and sat up and sat on my chest. she stuck her hand like wayyy in my pants and i freaked out and started moving and trying to get her off but she wouldnt move she told me to relax and just try to go to sleep. i put my ipod on and listend to it while she did stuff to me until 3:00. the next morning she kept asking me to lay down so she could keep doing it but i wouldnt i want to tell her i dont like her to do it but i dont want to ruin our friendship or cause a fight. im 13 btw and she is 15