How likely is it that this was business only?

After a period of intense fighting my boyfriend and I agreed that our main issue was me not knowing what I wanted following him breaching my trust almost two years ago. So we agreed that I'd call him back with my answer. I really needed time to think, so I didn't call back with my answer until 12 days later.

Before I gave him my answer, I asked him if anything had changed, if he was seeing anyone of interested in anyone. He said per an earlier agreement he wanted to share that he was interested in an indirect coworker and had given her his business card. I asked him about her and gave me her age and said she asked his relationship status but that nothing romantic had occurred. He stated that he hadn't expressed interest and that the card was given in a business setting but obviously had his contact info on it.

I appreciated his honesty because he betrayed my trust before but how did he come to know the woman's age and why did she feel so comfortable asking about his relationship status if they haven't had any non business related conversation?

He refused to answer me citing the possibility of him answering those questions leading to endless questions. So I broke off our relationship, feeling that he was withholding damaging information or lying.

Am I overreacting?