Hello, I am Rafael. Thanks for asking your question - I'm here to support you. (Information posted here is not private or confidential but public).
I ma very sorry to now about this situation.
you please join the chat for us to dialogue about it?
What you describe here is for sure uncomfortable for your partner, but at the same time I would not say it is a serious issue, nor a reason for concern. You were married for more than 25 years and the name of your ex-wife was perhaps the one you used to be most for such long period of time, then it is normal and fine if you happen to use it without being aware of the mistake, once you did with the person who is now being your life partner. This happens with step-children, coworkers and more.
As long as you keep working on developing, improving and promoting further honesty, intimacy, trust and affection in your relationship, with good consistency between your words and actions , there should not be any problem or concern here. Just avoid spending more time talking about ex-wife. It was fine and perhaps necessary in the past but now it should not take any time - energy from your lives as a new couple.
Hope it makes sense.