Is my ex jealous that I'm talking to somebody else?

I’m 19 years old. I’ve been with my boyfriend for a year and a half. Not to long ago he broke up with me because I hacked into his myspace! My bad, I just had a feeling he was up to no good, and I was right. He was talking to another girl. I was pretty sad. The thing that I don’t get about him is that when he broke up with me, it seemed as if it didn’t really bother him at all if he lost me. He always told me he would never leave me, and that forever was forever with me and him. Another thing, I kept calling and calling him after he broke up with me, and all he kept telling me is that I need to find somebody else. About a month later, I started talking to this guy I had met before my boyfriend. At first I thought that I would just use him as a rebound, but I’m actually starting to like him now. It was already a period of time that I didn’t talk to my boyfriend, and then one night he called me, asking me if I was seeing anybody, I told him yes, I was. The part that confused me the most is that when I had told him the truth, he started to cry and tell me that he missed me and that he loved me so much, when I could’ve sworn that he told me I should find somebody else, I mean, he sounded at the time being that he didn’t want anything to do with me at all. But, unfortunately I got back with him, and that other guy, I’m still talking to, but what he doesn’t know is that I got back with my boyfriend. Did my boyfriend only get back with me because he found out I was talking to somebody else?? I dont get him..