You are right to be concerned. Your cheating may be “non physical” but you are none the less taking time, energy and attention away from your marriage. Fortunately, you have already taken the first step toward fixing the problem. You have acknowledged that you are putting your marriage at risk.
The next step is to figure out what is at the root of your behavior. Is there something about making a 100% commitment to your wife that frightens you? Is there something about the risk of being caught that excites you? Do you use the chatting to feed some need that isn’t being met in your marriage? Is the time spent chatting a way to avoid other responsibilities? Have you fallen into an addictive pattern? Those are just a few of the possibilities I’d want to explore with you if you were in my office.
It’s unlikely that just telling yourself to stop will do it. You probably already tried that and failed. Since there is no easy one-size- fits-all answer to your question, I do suggest you see a counselor. A counselor will help you address the kinds of questions I outlined and understand what is maintaining the behavior. Understanding will help you know what you need to do to stop cheating yourself and your wife out of a solidly committed relationship.
I wish you well.