ok i did not read 18 pages of replies because thatd take forever... but heres what i think about your post.
it sounds like youre pretty disappointed with your life and where its going right now. the bad? the things youve come to realize. the good? that youve realized this and are willing to admit it.
its not going to be easy to change the path your life is going down, but that doesnt mean it cant be changed.
first off, i think you should talk to your best friend. he probably doesnt even realize how much you miss him, itd be too bad to lose your best friend because of miscommunication. over time friends are bound to grow apart, so you cant expect it to be like it used to be... although if it ends up like that, awesome. but let him know how you feel, how you want and are going to change. sometimes you gotta make sacrifices, and putting up with his ex-gf might have to be one of those... you dont need to be best friends with her, just be friendly.
as for the school/job situation... college isnt for everyone. and if its not for you, thats ok. if you really think it is for you, go talk to your high school guidance counselor asap about what you need to do and options that are good for you. you may want to consider a technical/community/2year college instead of a "normal" college, since it costs less and will get you a degree in less time and less work probably... because no one wants to work min wage their whole life. but do some research online about it, talk to your parents, and talk to your hs counselor.
you said you do many things wrong... i have no idea what this might be. misbehave at school, drink/drugs outside of school... who knows... and it really doesnt matter. you know what youre doing wrong, so change it. if its because youre bored, find better things to do, find a purpose, find something meaningful to replace the bad things. but if you know youre doing something wrong, dont keep doing that. thats stupid. obviously by having the courage to talk to people about your problems, youre a strong enough personto change too.
always remember, you control your destiny. its not too late to change for the better. youre still in high school. if you think that youre screwed already and give up, you will be screwed your whole life, and it will be so much harder to change things later on. you may lose a friend or not get what you want exactly, but now is the time to change anything you want, however you want it.
good luck, and best wishes!