Bf texting same girl all the time

My boyfriend and I have been together for 2 yrs and have a baby together. He has had a female friend that he met way before we did. In the beginning of our relationship when I was pregnant he text this girl all the time and she text him a lot even when she knew he was home. I told him I didn't like that she didn't respect our time together when we are at home together and on weekends when we are off work. I asked him to tell her to respect our time while at home together since they already were texting all day while at work. It seemed to quit but now a year and half later I've noticed that they still text so I went thru his phone and saw tha they text everyday. She texts him whenever she wants rather its 6am or midnight. She lives out of state and they haven't seen each other in at least 3 years. Last Christmas she asked for our address and she sent a card to him but I never saw it an I know he sent her one cause I saw a text saying he sent it but he never told me about it. The text seem very innocent unless he is deleting some but I've noticed the times he text her is like when he leaves to go to the store for us he texts her while he's gone or one day I left the room to check on our daughter who was outside with my parents he text her as soon as I left. She has been sending him pictures of herself an her daughter and of just her in her Halloween costume. Just seems very wrong she knows we are a family and doesn't care about me or my daughter. I got her number an i am thinking about calling her myself just not sure what to do. We are 25 yrs old and plan on getting married and are about to open a business together just need to know what to do about all of this. Is it an emotional affair?