I don’t regret the things I did wrong. I regret the good things I did for the wrong people.
This might come across as quite strange for regretting doing the right thing, but after being messed around by people you can easily feel regret for wasting time and energy on people that didn’t deserve it. What you need to remember if your conscience is clear. You did the right thing and now they have lost your help.
Rather than asking yourself how you should change, why should you be the one with regrets? That is on them and one day they will be surrounded only by people of a like mind; a group of unworthy, using, enabling people trying to out do each other while we are happy and content.