Life does indeed suck. And really, there is no point. I guess we just make the best out of it and try to better ourselves.
I don't personally have any anger issues, but I have had "friends" like that before. I went to baptist school and so much like you, I have the personality of a christian. I have been used as well and it does make you feel like a piece of crap. Why do I let people do this to me? I don't really know. On one level I think "fuck it, it's just money, drugs, whatever apparently they think they need it more than I do" I try to be compassionate, and it's really shity when people act like dicks after you were kind to them. Really it shows a lack of character on their part and there is no use in beating yourself up about it. Basically I just dropped those people. I want to surround myself with people who love me for who I am, not what I have to offer them.
It is hard for me to tell people who I may have once called friends, to fuck off. Once I did I felt better about myself, I guess empowered might be the word....
I feel like I am more angry these days, but I guess I just remind myself that it's pretty much a wasted emotion. Not to long from now you will forget what exactly set you off. Not much longer after that you may forget ever getting angry.
I guess in general I'm just an optimist.
As for the rest, just try to eat. Low blood sugar is terrible for my temper.
Try to relax and take life as it comes.
Are you able to move? Perhaps you want to find a new second job? Maybe a few adjustments in your life will help. Helps me anyway, I move allot. Another thing I do when I feel life is pointless, stupid, and dull, is I do character cut ups.
Its pretty fun and brightens me up.
Basically the point is to shake you up. Step outside your box and experience different things you may not have normally.
Make two lists, one of things that boar you and another of things that terrify you. Now try to combine them. For example if classes boar you, and you are terrified of public speaking, perhaps you would prepare a lecture and recite it in public space. Of course they don't all have to be as crazy as that, but the point is to break from routine and meet people, make stuff, do things, whatever.
Sometimes I sing loudly on the bus, sometimes my friend brings his guitar. Sometimes people love it, sometimes people demand to be let off the bus RIGHT NOW. I don't need those people to like my singing, but I do need my life to be fun.