Advice please, my brother's a tool

I'm having trouble with my younger (21y.o) brother behaving like an apathetic obnoxious tool...

My bipolar doesn't make sense in his logical mind, so it's not validated at all. My solution to that situation is to not talk about how I feel. BUT... He still gets to moan rant or gloat bout his life, relationships and whatever... So I just sit there and listen.but i feel it's UNFAIR! Why does he still get to share?? He invited me to go hiking, when yesterday came around I really didn't feel like it, so I graciously declined. His response was to guilt trip me for 45min straight, and when that didn't work, he switched to insulting me for 15min. How I managed to hold my tongue instead of bash his face in is beyond me, (yeah I got temper issues) but I'm proud of my lack of response. When he got home he tried to strike up a convo like nothing happened. If that wasn't awkward enough, he told me he feels hurt that I didn't enquire about the hike, I DON'T CARE ABOUT THE STUPID HIKE! thought I made that clear... Argh

Anyway thats just a drop in the ocean, his favourite response is "I don't care", or "that doesn't affect me", or "how does this affect me?" he's always been a douche but he's worse after our dad passed. He's mean, obnoxious, demanding with a filthy superiority complex. And incase I wasn't clear, ONLY his opinion counts.

I suck at finding balance, I'm black or white, all or nothing, problem is, I don't want it to be 'nothing' between us, but I'm struggling to draw the lines and set boundaries... I know he's an arrogant fool, but I'd like to have some semblance of a relationship with him, our other siblings are WAY older than him (I'm talking bout 15-20yrs older) so I know he doesn't really have relationships with them...

Any ideas on how I could possibly have a relationship with this dude without investing too much emotionally?

I did not see anything in what you related that would have bothered me in my brothers' behavior (I have three). That he wanted you to go with him on a hike; you find that objectionable? My brother, at a high school football game, we were both in the same school, I went up to him to borrow some money for a drink and his date said, "Gee, Pat, I didn't know you had a sister!' and his reply was, "I don't publicize it." Your brother wants to be with you, obviously "likes" you.

He does not "get to" moan, rant or gloat," you sit around and listen? If you don't enjoy listening to him, use his "I don't care", "That doesn't affect me" or "How does this affect me?" lines and leave.

You cannot have a relationship with someone without investment. However, it does not sound like you enjoy this brother much so I'd not bother with him much, would find another friendly guy to start a relationship with like the brother you would like.

There are moments I like him, his sense of humour is top notch. But I just can't deal with how he is ALWAYS right, and he can be quite cold and downright rude ALOT of the time... My mom just shakes her head and 'threatens' him with prayer. Guess you'd have to live with him to know what I'm trying to articulate...
I can't say "I don't care" etc, it's N0T in my nature. I care even when I really don't want to... Thanks for responding tho.

I feel like I'm listening to by brothers dopleganger! Good greif! My brother berated me every minute he can. I only see him twice a year because he's in Ohio and I'm in Delaware. He tries to call but it always ends up in a sceaming match. He can't wrap his head around either my anorexia ( which I've had for 31 years) or my bipolar. He thinks I'm a deluded, selfish, self- serving B. He doesn't accept mental illness as an excuse and says I do it for attention and if I wanted to I could control it. I've has to spend my life in his shadow as well and he too is my younger brother! His stories and life has always been priority 1. Funny all my cousins have a nickname for him " the golden boy " bc in my families views the sun has always risen and set on his head. I advised him if were going to have any relationship were going to agree to disagree. I hope this was helpful. Peace and goodwill.

Thanks I envy the fact that you don't have to see him everyday. I think I'll give the 'agree to disagree' a go...