Gay dad in strained marriage

I am in my mid 50-s (blessed with great physique and looks for my age, but whatever). I married at age 31 to a very nice girl. We've had two great kids but have grown apart. I visited sex shops a few times in my 20's and when I was about 26 a guy gave me oral for the first time. About once a year I received oral from a guy until I was married and had a gay few fantasies as well. Shorty after I was married a guy I kind of nkew from college moved in next door. We ended up making out once and I found it very enjoyable. That really started my gay longings.

I had a couple of gay encounters during my 30's but in my mid/late 40's I really began questioning my orientation. While still married I sought out trysts on Craigslist (safe sex) and at one point my wife found out and went ballistic. I had some sex therapy/counselling and have told her off and on that I'm NOT GAY.

I'm a very together person but find myself increasingly anxious over my sexuality. I've obsessed recently over the online "Am I Gay" tests- both the amateur and the professional versions- and I come out with medium-high to high gay scores. My wife and I have sex once a week and I enjoy it; I masturbate almost daily to gay or lesbian porn/fantasies. I long to find a guy to make a permanent sexual and emotional bond with.

I'm terrified of shirking my responsibilities to my family but am still able to function as husband and father. She knows that I'm struggling and I'm still quite unhappy. She's jealous because I make friends easily and knows that if we end our marriage I'll land on my feet. My 22 year old daughter is on her way to a great life; my 20 year old son struggles and may himself be gay (so shy).

What to do?