I am really sad and have no one to talk to!?

OK so 6 months ago i moved to America from the UK and as you can imagine i was very homesick (like self harm homesick) and never told anyone about it as it got better within about 3 months but i have suddenly started feeling like this again and have started to self harm and even thought of suicide. The worst part is that i have never been able to talk to my parents about anything because in their own words they are not my friend they are my parent. Usually i would talk to my best friend and she would give me a hug and i would start to feel better but obviously i cant do this now as i don't know anyone well enough to tell them this and last time i did it ended up becoming a rumour and i had to lie to the counsellors about it. I keep over reacting to everything my brother does and even he is starting to pick up that something is wrong and he is 11 (i am 13) . Please help and give me some advice because i am scared i am gonna do something really bad and that i will regret..