This will seem like a lot of irrelevant information but it will make sense.
I'm relatively new to tabletop RPGs, but not RPGs in general. A little while ago, I became interested in playing with a group that my older brother participated in that uses the Shard RPG. I Skype-in to play. I learned fast and the character I wanted to play was what they were missing from their party, so they were more than happy to let me join.
In Shard, you play anthropomorphic characters. This group is really - and I mean really - into the furry culture. They have integrated it into the game. I don't care that they are proud furries. Like what you like, you know?
One of the issues is that they talk over me and interrupt me when I talk. So much that I don't see the point in trying to speak up any more. I now get in roughly 2-5 role-play minutes to their 20-45 minutes each. I'm not exaggerating because I record the sessions - they wanted me to write a book for them. It's not truly role-play, either. Instead, it is to get information to get to the next fight. As a result, no one in our party knows each other beyond familiar acquaintances.
The main thing is that they are extremely condescending. They consistently assume that I am the dumbest person in the group and routinely make fun of me. They do not let me defend myself properly, due to the above-mentioned interruptions. My brother lets them. I'm not expecting him to do my fighting but I didn't expect him to just sit back and watch.
The GM is a mess. He makes excuses like, "because I said so" and "that's the way my world works." For instance, I gave him real-world information about speed and he used it for an NPC. Then later, after the session was finished, I mentioned how a certain animal has this speed (because I thought it was cool and wanted to share) and he said, "That's not how mechanics work," in this derisive tone. Everyone laughed. I tried to explain I was just sharing something cool but since I was Skyping in, my brother hung-up right as I was mid sentence.
They, particularly the GM, have done this before. Where I provide information no else seems to know and they use it, but don't let me use that same information. The GM uses it for his NPCs and the other members' characters, but not me.
I have left before and I kind of dread being around them. On the other hand, I don't really have friends (woe is me. Maybe I'm the problem?) and I like the creative aspect of it.
TL;DR
I am playing in a disrespectful group. One of the players is my brother. They talk over me, interrupt me, condescend, and at times are openly aggressive. They spend more time arguing with each other than playing. They have aggressively told me to shut-up when I got confused and asked a question. They make rape jokes even though they know I've been raped, repeatedly. The DM is a mess and makes endless excuses for not planning his story or NPCs well.
I have tried talking it out with them to no avail. It is a five person monologue to rationalize their behavior. Should I just stop making my weekends frustrating and leave the group?