My boyfriend has a new work friend....

My boyfriend and I have been together for a year. He's one of the nicest and most generous people I've ever met. Since he cares a lot, he tends to get involved in other people's lives trying to help. Recently he met this girl at work, and apparently she's a mess. They text often every day, and before it didn't bother me, until Friday. She's recovering from an abortion and isn't coping well. I'm sympathetic to that situation since my boyfriend and I had to unfortunately follow that route, it still affects me today. He wanted to tell her about our situation, and I had to say no. He's the type of person to use his life as a lesson, which I can understand, but I didn't want to share this part of my life with someone who I don't know. Fast forward to 2am and we're watching movies. He gets a text and I think nothing of it. I use his phone a few minutes later and see her texting him. I'm not a jealous woman, but that shit had me irritated. I know that he's not the type to cheat, but it still bothered me. Since we already had that discussion on what not to share with her, I didn't want to have another conversation about her texting him at 2am and seeming like the crazy girlfriend. Especially since they work together and I don't want to make their friendship awkward. I'm also not the type of person who feels like I can dictate who my partner can talk to. Am I overreacting? I just don't know.