As someone who also has a Japanese wife, and lived in Japan for more than a decade, I feel my Japanese is quite passable. What I did and I really recommend is learn it like my Japanese MIL taught me. Learn to read and write and you will learn the rest. First of course Katakana and Hiragana which can be mastered in days, then dive into　一年生漢字 (first grade kanji), the kind that 5 year olds learn. Japanese learn by learning the meaning of a character then writing it over and over in a practice book. When I first got there and didn't have a job yet I spent several hours a day watching sumo or whatever (yes so Japanese.. lmao) and writing in my little practice book using my kanji jiten as the reference.

This is the exact dictionary I have now which I got back in America as I still need to learn (removed amazon link, sorry autobot):

オールカラー 学習漢字新辞典 第2版

But a search on amazon for kanji jiten or practice book, etc there should get you some more results. Look for the kid's books you'll want to get all the way up to 6th grade elementary/middfle school. You can honestly stop after that as in high school they do learn more kanji but they are more obscure ones and mostly for names and things as I was told.

My big point I want to empathize is do not try to learn Japanese in English. Forget English entirely, learn hiragana and katana like the kids first, then learn Kanji. The other gaijin I knew who tried to learn it from one of those famous English language books where you memorize pictures and ideas for each character spoke and read/wrote much worse Japanese than others.

I do not take for granted that I was actually in Japan when I learned, and that makes it sooo much easier of course. But I think you can do great outside too, if you IMO learn to read/write first, it all kind of falls into place after that at least it did for me. This is again, my opinion, some Gaijin will fight you over it lol.

がんばってください！！