Am I wrong to feel this way?

My boyfriend of over a year now, in a serious/committed relationship, has not, not will tell his ex-lover/girlfriend about us, she still emails, calls from time to time and leaves messages and now just called and emailed him information on a function, asking if they could meet there. He stated that he simply emailed her back stating that he was busy that day. I only know that she called him, because she called him on his cell phone while we were on the telephone together last night, our usual time/conversation and we both commented that who could that be this time of night calling. He offered to go and get his phone to check if it made me feel better and , I simply stated that I am not concerned, that I know he loves me and I trust and love him. The next day, we were discussing our upcoming weekend/and arrangements to be made and I asked By the way, who was that, that called last night?" He then got a little short with me on the phone; I offered that I didn't mind if he wanted to go, I love and trust him, he then stated, "I don't need permission to go." and we finished our conversation and we then ended the conversaiton with him stating that "We'll talk later." No, I love you's etc...I emailed him in the subject line simply stating "Ouch" ...Am I wrong to feel that he needs to deal with her and let her know about "US" ?