Should I tell my wife of 35 years that I am gay or live a lie?

You are right, your homosexuality is a deep part of who you are. You are now faced with the decision to either disclose or keep silent. Only you can make this choice.
You have been attracted to men for decades and have struggled with your sexual orientation throughout your long marriage. You may have thought, when you entered a heterosexual relationship, that you would settle and ‘forget’ about your preference. Also, 40 years ago it was very difficult to come out as gay. Societal attitudes to gay and lesbian issues were often hostile and unforgiving. And, so you met a woman and took the marriage route with her, despite being attracted to men. It is a commitment you obviously took seriously, as you have been faithful to her through the years.