What do i do? (╥﹏╥)

I'm sorry. Theres something i wanna share, and it would really anger the people but please do guide me.
My cousin is in class 10 right now, going to give her boards. I had never really spoken to her before, but there was some sort of spark and we really really opened up to each other. We became seriously close in 2.5 months. Im attracted to her.
I'm 6 years older than her. I had a serious problem of somehow getting sexual with any girl who slept close to me ( a guy who was introduced to porn at the age of 9), i told her that and she said that she'll help me cure it. She did. Its much better now and im in very much control of my actions at night. But. I cant stop kissing her. Im not able to. Ive gone sexual with her (just an orgasm over cloth). And these days she wants more. Its becoming really hard to resist. Ive tried to stay away, but theres always this emotional drama of me not being able to give her time, she getting angry and not talking to me, hurting and cursing herself, and what not. I got super close to her for one main reason that she hurts herself, a lot. And im scared she might take a big leap. So i keep her in check. Shes had bad trauma in the past, being sexually abused by her best friend, that keeps popping in her mind making her go crazy at times. I care for her a lot.
Yesterday she told me in her sleep that shes started having feelings for me. And yes i know im supposed to act mature here but, i do too. This needs to be removed.
Im going to leave this place in the next 20 days, and i know its going to completely destroy her cuz no ones been this attached to her ever. She shares literally everything with me from what she ate to when shes got to change her pads.

How do i proceed. What should i do. Its alll my fault. I dont want her exams getting fucked up because of me.