Should I tell him that I suspect he is still cheating?

I am 58 and my husband 45 we have been married 23 years have a daughter who is 21, last year of uni. I found out 5 years ago that he was cheating with someone at work. At the time we were not getting on, don’t know if it was because of her existence, but he was always angry with me and very critical of everything I did. We stayed together, me because at my age I didn’t want to go looking for anyone new and was scared to be on my own. Besides, I had to think of my daughter who was studying and needed both our support. Him? I am not quite sure whether it was because of the money, as he would have had to lose half or maybe more of everything or whether because he felt bad abandoning us. He kept saying that it wasn’t because of the other woman but he wanted to be free. For the past 2 years I couldn’t have wished for a better husband. His attitude to me has changed. We hardly argue and spend lots of time together. Although I don’t tell him I love him, he tries to tell me in a jokey way, but I must confess I don’t completely trust him and am wary of his motives. Last night I asked to borrow his pen and was surprised that it was the kind of pen a woman would choose, it had Treasure written on it. I asked him where he got it from and he said he had bought it for himself. I know that this isn’t the kind of thing he would buy and he is so mean with money, he would never buy his own pen when there are lots of pens around the house he could take. I don’t know if I should spoil our present harmony by telling him that I suspect some woman has bought it for him. I know I am being childish, but can a person really change so much and what would make him change so?