From the archive

You're not a good person. You're just afraid of conflict

And no, you don't need to turn into a rude bastard to do this. Some people discover personal boundaries and start behaving as though they've bought a license to be an asshole. You can calmly say you can't. You don't want to. You're not willing to discuss it. You're not going to lend them money. You don't have to humiliate the person asking or lecture them about your new personality.