The advantage of having like 10-15 years on most people on this forum is the fact that I can say this from experience. People will stop considering you an asshole if you stop acting like one. There is never actually a too late on that. I've literally watched people's entire interaction base with a others change over time, like a little asshole sprout turning into a mighty social anchor.
I have also watched people completely sabotage any hope they do have of that by turning right on fork in the road with the sign that reads "Nah bro, people are always going to call you an asshole, so you'd better act like it, you're not good enough to do otherwise." Yes, there's a weight to overcome, but the only reason people will keep thinking you're an asshole is if you keep being one. As soon as you go "well, I'd better stop trying to be better," you instantly kill all of the work you've done before you even start seeing the benefit.
Reputation is function of your sustained interactions with people, and no matter what you want to be, you just have to keep trying to be that to other people for long enough. Be honest. Be upfront with what you're doing. "Hey, I'm trying to be a good person, call me out if you think I'm being shitty so I can become better." Being sullen is basically the least helpful thing to be if you genuinely want to go for it.