Serve, I've been in your shoes many times. I've deleted the cuck porn from my hard drive and foreswore it, only to fill it up again within a short time, often with even the same material.
Like you I have a wife who loves me, who I please in bed, and who probably would not be into this sort of thing.
I used to think just like you, wishing that the thoughts and desires didn't turn me on so much, that my life would have much less distraction if these fantasies didn't occur.
Like you, I thought maybe it was self-esteem issues, as during my teenage years I was pretty hard on myself, and as a result had massive jealousy issues with my girlfriends; needless to say, that destroyed a few relationships.
However, as an adult, my self-esteem issues went away, but the cuckolding fantasy didn't. Neither did my problems with jealousy.
I spent a lot of time in reflection upon this, not wanting to ruin my marriage over petty and exaggerated jealousies. I found something out about myself. My jealousy and cuckolding fantasies were intrinsically linked.
Since then I've accepted that I am, at heart (thought not in practice) a cuckold. It was a line in a movie that said it best, in my opinion: "Jealousy is the best aphrodisiac."
Since I've accepted this, I have no jealousy issues clouding my marriage. Of course, I'm not a cuckold either, but I've come to accept that the fantasies do NOT have to make you a "wimp cuckold," a lousy lover, or someone who has a low opinion of themselves.
Maybe you'll see something of yourself in this, or perhaps not -- as it's my direct experienced, your mileage may vary.