Am a 19yr girl in an boarding school in abroad and I had a sexual relationship with a girl in school and I regret doing it and I have the feeling that I am bisexual but I don't like it What should I do to get rid of this feeling.
If you are really bisexual, meaning you feel attracted by both men an women, you have the option to lead a life with a husband, it will be the easier way of life to live this option.
If you are in fact clearly lesbian, meaning that you do not feel attired by men at all, Islam lacks an answer for the question what to do with your life; see this question. Although the question is not actually specifying gay or lesbian, the answers in there actually refer to gay people.
As to lesbian women, the particular interdiction of homosexual acts is rather extrapolated because it originally refers explicitly to men. It can however be concluded from the interdiction to have sex before marriage that there is an interdiction, too, as lesbian marriage has never even been thought about in the times of the Prophet or long time after.
Assalm o Alaikum The Holy prophet P.B.U.H has told us to read a Dua in such a condition when you are stuck in a habit you want to get rid of that... So this is very useful دعا.. Please try to read this dua more and more. رَبِّ إنّيٍ مَغْلُوبٌ فَانْتَصِرْ Rabbi Innee maghloobun fantasir...
Insha, ALLAH you will get rid of that habit