Am I overreacting?

Little back story....

My bf and I have been together a couple years. A few times I have caught him texting ex’s or other women. Nothing too big. Except that he would call them “hon” and “sweetie”. Most wouldn’t reciprocate except one ex. He doesn’t talk to her anymore because we talked all of them out and I told him if they aren’t willing to be friends with me, come over for dinner so I see they aren’t a threat, then they don’t deserve to be your friend. The ex I referred to in the beginning would text him in the middle of the night. Yea. I found a big problem with that one. Anyways...

We broke up about 6 months back. He had been talking with this other girl. Telling her he wasn’t happy when I thought everything was fine. She was nice and would give him advice. Run him out coffee while he was working and would be driving by her shop. Give him food if he was working and driving around....

See where I’m going with this? Yea. Not a good situation and I was completely uncomfortable. While we were broken up he went to her house for dinner.

He swears nothing happened. I asked a mutual friend of hers and mine and she says nothing happened. So I tried to invite her over, since my so talked her up so much.

She never would come. Especially after we got back together.

Him and I agreed that if she wouldn’t come then she didn’t need to be that close of a friend of his. He agreed. And nothing came of it until last week...

Him and I had discussed about having children. He doesn’t want any more. I do. It came to that point where I said we should think about things. He left for his place that night.

And he messaged her. First time in 6 months. He messaged her.

It was nothing bad. The old “hey how’s it going” “cool” “nice”.

But it bothers me. Like he actually does have feelings for her and is keeping her on the line just in case...

Am I overreacting about this??

And please, I don’t want to hear about how this is a “unhealthy relationship”. We actually have a pretty good relationship otherwise and rarely fight.

I’m only looking for advice.