Side chick?

So my husband (not boyfriend) has a girl on his job that's interested in him. She knows he's married. They text sometimes & I addressed this problem & told him I was uncomfortable with it a couple of months ago. So he texted her & told her he doesn't think it's s good idea for them to text because it makes me uncomfortable. Recently, they've been texting again & he's been initiating the conversations. She even said "I was skeptical about texting you this early because I didn't want wifey problems". (They work early morning jobs). She texted him & said how worried she was about him on a day it was raining. Before we got married he told me about her & how she wanted him. He admitted that she was attractive. This concerns me! & I recently found out I'm pregnant  so my emotions are all over the place. I'm debating if I should address it again. I just don't think that it's right for them to communicate outside of work. Yes, speaking to each other is fine, but other conversations can lead to other things. I mean, if you need a female to text...text me! I am your wife!!