I met a man whom I liked and later found he was previously a woman. Am I right to break up?

About a couple of months ago, I met a guy and we really hit it off. We’ve been dating since, but I started to notice that he gets really cagey whenever I bring up his past.

About a couple of months ago, I met a guy and we really hit it off. We’ve been dating since, but I started to notice that he gets really cagey whenever I bring up his past. I did some investigation without his knowledge and found out that he had a sex change operation a few years ago. Am I justified in ending the relationship?