Lie or not a lie that is the question

My husband and I had a petty discussion/ argument. We moved states 7 months ago. Throughout this time, I've asked if he has talked to or heard from a specific female/ex- coworker. Over the months, he said no until recently when she messaged him Happy Bday and Merry Christmas. Fast forward to today, a message pops up from her... before his phone locked.... which caused me to look through their messages. All platonic, but he had been messaging her since the day we left (7 months ago). (I know I am wrong for going through his messages). The argument started from me simply asking him why did he lie. He said he never lied and that messaging a few times here and there is not talking to someone/keeping I touch. So.. did he lie.... Or not lie? We both have male and female friends . The insecurity for me with this coworker is that he has lied in the past about them going to lunch together several times. I found out by her telling me although when i would ask him if they ever had lunch together at work he would always tell me no. He also told me he never lied about that either because going to lunch a hand full of time is not going to lunch with anyone. I feel like he is gaslighting me and twisting stories to make him not look in the wrong or maybe im just crazy.. he says I am making him out to be this big liar that he isnt.