read my last post and you will get the answer recounselling. and how i've done heaps over the years it didnt change anything
so i do seek advice, maybe speak to a counsellor, parentline or such is great, but regular appointments, giving my life to that , no thanks, i am not giving my life away more years becasue of people around me.
I read your OP and didn't see anything about counselling as this was going to be my first suggestion to you.

if you were willing, and wanting to work on it, counselling may help you become less of a victim. It sounds like you have had a hard time, but you need to decide what you are willing to put up with, and to not accept other types of behaviour.
I have to say I agree with Kate here.
Finding a counsellor is a bit like finding a car - your not going to buy the first car you see, you usually shop around. This is just like counselling. Not all counsellors will suit you.
Yes you need to vent about what is happening but while ever you have thoughts like
but regular appointments, giving my life to that , no thanks, i am not giving my life away more years becasue of people around me.
you are only giving those people around you more power and permission to walk all over you. You need to start taking back some of this power and not keep sitting in a victim role.

It sounds like you have been through allot, but YOU have the power to change how people treat you and your reactions to this. If you don't stand up for yourself, then people are only going to continue treating you this same way.

my mother often has been a psychopath enjoying watching me in torment and encouraging others to torment me and i so often wanted to die from the torment she puts me through at times,
Maybe until you are able to cope better with your own thoughts and feelings, this is one influence you need to step away from for the time being, work on yourself first and then work on this relationship and ways to better cope with it.

Good Luck, it's hard work, but like I said, only YOU can change how you react to these situations. And yes, teenagers can be selfish etc - maybe it's because they don't yet have the life experience to cope and/or understand the full extent of the situation and maybe sitting down and being honest and Telling them will help them to understand a bit better.