What would be the possible reason why my ex boyfriend is angry with me?

I mean I already let go of him and he's so happy about it. Is he still affected? because somehow he knew that I lied to him about resigning my job. Is it possible that he still cares for me? But he starts saying bad words to me. Oh! how I would love to hate him but I can't. I don't want my incoming year to be filled with so much bitterness and everything! Please help.....