Hi to everyone!

Am just feeling so sad and I don't know how to deal with my feelings...
I don't know if am just jealous and insecure but I saw my husband enjoying himself
In a conversation with his female co-worker and close friend I think.
He didn't even felt my presence that am just meters away from them. He is
Very close to this female and when I asked him what's going on between them, he said they are just friends to the extend that he will used pay phones to call her and not his mobile phone. They have been together at work for the whole day then they still text each other and call even at home... but he deletes any text messages and phone calls and he is hiding everything from me because according to him I am jealous of everything he does and that's why he's hiding their conversation but he goes out with her during his day off.
Which according to him is nothing but a friendly date... he was never like this before.
I am confused whether to listen to my instincts or maybe I was just too jealous and insecure I making myself believe that something is going on between them. Because he even chose to stay late at work than to go home and spend the rest of the night with me. I don't know. It's hurting that I don't know yet how to share everything clearly.
I don't know already how to react about it in front of him and don't know if I'll just ignore or what...