So, I want to do some martial arts, for self defense. Ideally one that will be useful without giving me CTE, or any long term bad stuff, even though I feel this is already asking for too much 
I don't live in the U๐๐ so gun related stuff isn't really an option.
I'm somewhat heavy, with a year of experience in lifting, and my cardio is not the best, but I can do long walks (of 1 or 2 hours) before getting tired.
I'm going to move to a bigger city in September, and there's a lot of stuff available, so you can comment on the more niche options.
So yeah, any advice from your experiences is welcome lol
If I had known people started arguing over my post I wouldn't have made it.
Qin and 389 provided good suggestions. Both judo and bjj are excellent options. Practical and low risk of injury if you aren't planning on competing. There is still some risk, especially early on as your body learns to adapt to the movements and you learn how to breakfall and roll correctly. I tweaked my knee the first week trying to stay upright when my partner was pulling my body. I instinctively tried staying upright but you're supposed to go with the movement. Don't let that scare you though. If it's an option, try to find a bjj gym that incorporates judo, so that way you can learn takedowns and how to properly fall if someone catches you by surprise. Either option is a really solid defense strategy and lots of fun. I am partial to bjj because I do it and had a few misconceptions beforehand that were quickly shattered when a lot of my preconceived notions about what the martial art looked like and what type of people go to these classes was flipped after seeing it firsthand. Yes, there are a lot of chuds in these fields, especially bjj, but you just have to be selective when looking at gyms. I find most chuds gravitate towards Gracie Bara gyms (they also have weird rules other gyms don't) and 10th planet gyms (lots of Joe Rogan chuds and then you get to have the endless debate of gi vs no gi), but again, these probably vary from place to place. Just check out the prospective gym's website, do a free trial and check the vibe you get from the students and the teachers. I picked my gym based upon the fact that: they did both judo and bjj, everyone was smiling instead of trying to look tough, and they had a trans flag proudly displayed and no weird chud shit.
But basically, yeah, if there's judo available take that. If not, do bjj. If you find a bjj gym that does both, definitely do that. Hit me up if you have any questions.
Edit:
Some more advice to help you narrow down your decision.
If you do decide to do bjj, look out for these red flags: Avoid gyms that make you pay for belt promotions. Avoid gyms that force you to compete. Avoid gyms that don't have women in the classes. Avoid gyms with contracts.
Judo in recent years has focused more on ground submission grappling (ne-waza), so with judo you'll do some submission grappling. Though still, BJJ guys are far better at ne-waza than judoka.
I think that would be like finding a unicorn where I will live (somewhat close to where I alr live, there won't be much of a difference