I'm the same as you. Random acts of kindness make the world a better place, and I am quick to help friends or family in need when I can. Sometimes I get taken advantage of, sometimes I don't. At the end of the day I know that those people who took my generosity for granted have to live with that. I understand you're angry, and hurt, but don't let someone else make you a cynic. Stay good and kind for yourself because that's who you are, and you'll always know who in your life is worth keeping around by who appreciates and reciprocates.