Dont know what to do

Ok. Heres the thing. I am in 7th grade and there is a 6th grader who is really pretty and we like each other but my friends keep saying mean things about me liking a 6th grader. It gets really annoying but i really like her. Also, there is this girl who really likes me (in 7th grade). She trusts me with her life but she is very unnatractive and i really dont like her. The 6th grader is her next door neighbor annd just saying the 6th graders name is eleni and the 7th is sarah. Eleni got a boyfriend and so i still like her. Sarah, since she "loves" me, says that since eleni has a boyfriend i should date her. Since i said no, she is really upset and she wont talk to me and i try to tell her that since i like eleni i cant date her but she wont listen. If u liked someone but they were taken, would u just date some kid who reallly like u even though u dont like them? Sorry this is so long but now eleni doesnt like me anymore so i dont like anyone so i am soooo connfused should i date sarah or just wait until eleni is available or? I just dont know what to do because sarah is all sad and droopy and whenever i try to talk to her she just wont listen so i dont want her to be sad about this but i dont want to date her and by the way, she absolutly HATES that i like eleni. So please reply, thanks i guess