Afarid of losing my best friend after High School because of many problems in our life

So, I have a best friend and I'm afraid that everything will end in two weeks when we will finish High School due the fact that she has some problems with her family and she is stressed out about this and trying to learn for the exams to go to college. Her family is manipulating her and I always tried to help her. The thing is that things are getting worse and it's 2nd time when she changes because of them and I feel again that she can gave up on me and move on away from everyone.
I'm getting tired of this things, I couldn't wait to go to college with her and escape this life and from our parents ( I don't understand with my mom that I live with, my dad is in another country, my parent break up when I was 4) and things are bad again in the last weeks of the High School and then we have to go to college.
She gets into this bad mood everytime our class master (I don't know how is it called in english) tells things about us.. he things that we are lesbians just because we go everywhere together and he knows that we lived together before (she was living with me before for 1-2 years because she wanted to escape from her parents). She says that the others see things better than the people in a relationship or friendship.. but this not true, many people are stupid and they are know how to use others for their interest, friendships and relationships these days are not true, there is no love and when they see this kind of relationships they are tinking that this people are together and they make fun of them..
I don't know what should I do again, she looks tired of being so close of me because of them and her family that tells things about me.. I'm getting tired of this and I don't want to lose her, I met a good friend and there are not many people like her in this world