I know what you are saying. I had that dilemma about throwing out cottage cheese when I decided to go vegan. I decided it was better to eat it than add insult to injury by wasting it .. what's done is done and the proceeds of crime had already been reaped. You can't fix the past.. you can only affect the future.
I would keep your car. Next time you get a car I'm sure you will make different choices. If it were me I'd probably have to get some seat covers tho. A leather or suede coat I would definitely not support continuing to wear since you're out in public with it and it would be more like advertising and promoting it. A belt is much more discreet tho, so would probably not generate any interest unless the person wearing it is super hot. (lol). Those are my opinions and I would just encourage you to do whatever feels comfortable and 'right' for you.
I think you have to give yourself a bit of flexibility or you will go crazy. The world we live in is inherently cruel (aka circle of life) and no one can be here without having an impact. If you enjoy philosophy at all, Ayn Rand has an interesting take on how moral and practical live on opposite sides of a spectrum. ie. No one can ever be completely moral. http://aynrandlexicon.com/lexicon/moral ... otomy.html
You are right about judging others... it is best not to. Judging them will not change anyone and in fact will only result in making them cling harder to whatever beliefs & justifications they are clinging to. Judgement makes people more resistant to your thoughts and ideas. So, it is best to just lead by example. ie. Be the good you would like to see in the world. I grew up with alcoholism (in my family) so I'm fully aware that it is impossible to change others... gotta just go with the serenity prayer and realize that you are the only one you have control of in the whole scheme of things.
If someone makes an attempt at being a kinder person, I wouldn't shoot that down or you will kill the attempt entirely. Instead encourage it .. build on it.. just don't push. And you may be surprised when someone actually takes the next step like you did.
I'm not sure the 'discomfort' with people food choices ever goes away. But I try not to focus on that and instead focus on what I enjoy about whatever person I'm with. And sometimes I practice patience and forgiveness when I start to feel discouraged. (Forgive them father they know not what they do... sigh).
I like this TED talk (3 minute talk) about the 'lone nut'. It kinda gives me hope that the world will one day change. http://blog.ted.com/2010/04/01/how_to_start_a/