I should just become an asshole

I hate being the person in this family that gets guilted into doing everything. Actually I hate be that person in general. My brother calls me out of the blue and says, "Can you pick me up at the train station in 45 minutes?" I really don't want to, but am I gonna tell him no when I have nothing going on right now? I want to, just cause I've picked him up several times before like this. But I can't say no, because I have a guilty conscience. Having guilty conscience makes me live life fearing regrets and the worst possible outcome. I also don't want to be an asshole if I can help it, but it's not fun being walked on consistently. I'm always the guy who you can count on to be there if you need something, and I'm available to help. That's great and all, for the other person, but I feel like I don't get that same consideration from everyone else. I'm always the one that cares what other people think and feel (except when I'm hanging out with friends and just spout out random shit that can offend people). I'll go out of my way to make someone else happy, even though I might not get happiness from it. I'm the one that shovels the driveway when asked. I'm the one that vacuums when asked. I'm the one that will drive 20 mins both ways to pack up shit and then figure a way to get it to shows. I'm the one who always feels I'm being taken advantage of. And when I push to do things my way, I feel beyond guilty, and things seem to backfire. But whatever, i'm probably overexaggerating as usual.

On top of this, my car went to the shop and seemed to fixed, but of course, the problem wasn't 100% solved, so it's looking like I'll have to attempt to sell the thing (I'll probably get $1000 for it at most) and buy a new/certified used car that will wipe out my entire savings/checking, or at least keep me in debt to my mom for the next 3 years. This is on top of the cold I have, which is clogging my sinuses and putting pressure on my head and ears, leaving me in pain. My friends also haven't called me back to tell me what the situation is for this weekend, so I have no clue what's going on. And I have my first class this semester: 8:30-10:30 PM. Fantastic time, I know. This is on top of the normal issues I've decided to center my whole thought process around. I've really got nothing to be excited about, that's for sure.