Don't let anyone take your kindness for weakness. Don't allow anyone to continue to treat you less than you worth. At some point you just have to call and spade a spade, cut your losses, and never look back.
Stay strong and remain kind. I allowed anger and resentments of the arrogant to take my kindness from me. I'm just now learning to regain that inside me, which makes me a much better version of the real me! Never allow anyone to dull your shine!