Foot Fetish

As long as you don't rely on feet alone to get sexually aroused, i don't see a problem in having a sexual preference for feet. I have the same. I enjoy my SO's feet as well as her boobs. As long as you don't watch other womens feet regularly or look them up on the internet, it is fine. As long as you don't overly focus on your wifes feet alone during intimacy, it is fine. And also of she is fine with it, it is fine.
The most important thing is to stay away from porn or porn subs.
Edit: also cut out M over pictures of her feet.
If you want you can M on her actual feet once in a while if she likes it.

 

I would not even advise to abstain from sex with your wife at all, in order to reconnect your brain to real sexual experiences. It is in fact useful to not ejaculate too often in order to avoid an overload of prolactine in your body, which weakens your sexual energy.
In that case it would be a good advise to minimize sex (with ejaculation) to once or twice a week. Or be intimate without ejaculating as often as you want.

I don't know what kind of struggle you mean you could have after rebooting.
As mentioned before, i also have a slight preference for feet. That means i like to watch, touch and lick my gfs feet as well as her lips, boobs, other specific areas. And that is okay if she is okay with it. Same with your wife.
Just cut masturbating to pictures. This might be a struggle at first. But once you abstain long enough, you can refocus your sexual desire to the real thing and therefore won't really miss the pictures.

Keep it going!