Different playstyles
You virtually say that you and the GM in question do not want to play the same type of game. The answer, as with so many things, is to talk to them. But the topic should be how to get into the same style of game.
If the GM is playing a mostly tactical game and expects most of the drama and fun to come in handling tactical situations, then trying anything else is going to be at best unfun for him and probably won't work well. Remember, if he has spent a lot of time planning a battle, balancing it against the party, possibly custom making maps, he is going to be invested in seeing that battle happen and understandably reluctant to a non-combat resolution. There is nothing wrong with a mostly tactical game, as long as everyone agrees that is what they are playing.
You seem to want either a wide open sandbox or at least a game with very light rails enforced invisibly, and you seem to want most of the action to come outside of combat. This is a valid style of play (and one I prefer), but it requires a GM who is good at improvising (not everyone is) and willing to set aside any set pieces he may have spent a lot of time planning. Not all GMs are even capable of playing this way (at least not until they have practice doing it). Even ones that can, may not find it fun.
Finding Middle Ground, or not
So, the answer, depending on relevant situations may actually be for you not to be in that game when he is GMing. It sounds like you want a very different style than the GM is providing. He is not providing you fun, but shifting to accomodate your style may very well ruin the style of fun he enjoys.
Less extreme than that, you could both consider shifting some towards the middle ground. He may agree to hide the rails better and be ready to hand you information, and go out of his way to make some of it useful for the upcoming battle. But he may ask you in exchange to focus your solution finding to creative ways to prepare for the combat rather than really avoiding the combat he has invested time in preparing.
For some examples of that, think about Wizards in D&D. They shine best when they are facing an enemy with particular strengths and weaknesses, and have had time to prepare for those in their spell list. You could be the one to learn the information about what they need to prepare for. The Witcher in that series is similar. He is a powerhouse if he loads up with the right potions and oils and traps...but needs to have an idea of what he is facing ahead of time to do that. A savy player could spend a fair bit of the game time researching the creatures to know what to prepare for (or looking that info up online). Your character could be like that, researching how to prepare and then doing the preparation. Batman is also like this.
Yes. You should leave.
These people are not respectful, and are not worth your time. Tell your brother you're not interested, and stop joining the call — he's the only person you have actual contact with, and given the behaviour of the rest of the group you're best cutting ties with them completely. (Who would want friends like that?)
You could expend effort working with them to overcome their talking over you, their negligence of you getting value from the game, and their aggressive and disrespectful behaviour toward you and making you feel uncomfortable — but that's a lot of effort, not likely to succeed with this group, and not really worth it when there's a world of gaming groups out there full of people who are quite ready to treat you and others respectfully like anyone ought to. (The fact they're making rape jokes in front of a rape victim is appalling, and one of several strong signs they're probably not interested in engaging with you constructively on resolving any of this. Indeed, a lot of what you've described reads to me as abuse.)
We have some guidance available on finding other groups that you might find useful, kindly gathered by a resident moderator:
Bad match with a gaming group, how to leave? provides general advice for politely leaving groups, but in this circumstance, you don't need to use it. The group does not need, and won't be receptive to, an exit conversation. (Your brother may be different in this regard, but you'll need to judge that for yourself.) Other people in the future may be receptive.
You mentioned these people were in the furry fandom — I'll advise based on personal experience that this behaviour is completely non-representative of that fandom, and exceptionally awful and heinous bullying by any standard, including theirs. Individuals in the furry subculture may be somewhat more inclined to poorer social mores than many groups, but the subculture is largely made up of harmless, well-intentioned, friendly individuals.
Roleplaying games should always be fun. If you're not having fun, talk and work with your group to resolve the source of un-fun, or leave and find another one. You found this one, you can find another.
(NB: In a previous version of this answer I'd unwittingly given some advice that appeared to suggest this behaviour was normal for people in the furry fandom. It isn't. At all. It's awful, and entirely outside any behavioural standard of the subculture.)
Best Answer
Assuming you told him your thoughts...
You've Already Done It
And the "it" is to not play with this person anymore
You've talked to them. You agree on some points and not others. It sounds like this person's play style doesn't match yours. That's fine, happens to everyone. I consider myself pretty flexible when it comes to play styles and there's still people who I can't play with. They aren't bad people, the just expect things I don't.
Quit playing with this person.
If you haven't talked with them fully..
Talk With Them Fully
Lay bare your feelings on the matter. If both of your aren't willing to work together to come to a happy medium then you need to say goodbye. You do what you should do an any social situation where there is discord.
Now, my final point...
Why did you cancel your game?
It sounds like it's an issue with a single person, not the entire group. Do group or friendship dynamics keep you from running your game? Are you jaded because of the experience? If you were having fun without them, just send their character to the void and keep on going.