HELP??? 10 PTS BEST ANSWER???? Is he just trying to make me jealous?

I broke up with this guy for genuine reasons, and he didn't mind. But then he saw me hanging around another guy and thought I was flirting. He was so mad. He then started dating another girl but would sometimes stare at me while talking to her. But if he's alone he avoids eye contact with me or acts resentful. And once when he saw me talking to another guy, he had this angry look.