My lifes just been going downhill and i've been thinking of suicide? please help.?

I really try to be a happy person but, ever since my life's been going down hill.. I really feel like I have no purpose here on earth anymore. It all started on here, I met a boy on here that I started to take a liking too, We dated for 8 months until he left and now I miss him more and more everyday. I have a boyfriend who got my bestfriend pregnant, she has cancer. Since i've never met my current boyfriend.. cause apperantly his mother has him on lockdown.. I have a really big gut feeling that my bestfriend from school, has been pretending to be my boyfriend jake and try and make my life miserable.. all i do is cry now. I don't know what to do. Anytime I ask her if Jake is fake she just says "i would never do that to you" But jake has had so much bad **** happen, it's making me very depressed. I'm very depressed, I'm almost fourteen and I feel like I shouldn't have to go through this..