Should I Apologize to ex Boyfriend?

Hi, My ex boyfriend wrote: “Happy birthday!” in a text to me on my birthday five months after we broke up. That day I was at that time of the month, had just finished an exam with no sleep or food. When I saw his message I was happy but nervous and then I wrote it was a nice suprise to hear from him. Then he just said “ok, take care then”. Then I wrote: “Why did you contact me?” because I wanted to know what he was thinking. Then he wrote: “dont be upset.” So I called him and said I wasn’t upset. Then I said I thought people weren’t supposed to make contact after a break up. I feel really bad about saying this. He then said angrily that he promised me he’d never contact me again. Because I had pms and was tired and stressed I reacted badly because I was defensive. Do you think I should apoligize?