Wow.
I empathize with much of what you are saying, the getting excited over every little thing you see on the street, the difficulty of broaching the topic with your wife, and the struggle of an imagination when you're tired and in bed but can't fall asleep yet.
Since I am currently struggling with those exact problems right now I will share my progress so far.
For things in the street I had an advantage that I wear glasses, without them every thing beyond two feet is a blur, I can still see cars coming and people walking but there is no clear picture, so whenever I am outside I take them off. Besides that you can try training yourself to always be looking down or slightly above eye level which makes it hard to see accurately any person or advertisement.
For talking to your wife I don't yet have any good ideas. my wife comes from a very sheltered home and I don't think she knows what P and M are. I have mentioned to her that there is a large movement in the frum world about shmiras eiynayim and that I'm trying to take it very seriously, which helped me explain the taking my glasses off on walks and getting a better filter on my computer. It might also work for when your uptight after a fall not to tell her that you fell but just that "recently I've been in challenging situations for shmiras einayim and it's very difficult and takes a lot of energy to fight the yetzer." but depends on your wife. And you are completely right that sometimes the wife just isn't in the mood to be together and you can't always get her in the mood. The only perception I've had on that which I found helped a little was 1) trying to keep in mind that being together with her is my way of taking care of her and therefore if she is not in the mood then it's not helping her. 2) not expecting her to consent. If you go in expecting to be together and get shrugged off, you've already gotten excited and will have a hard time backing down afterwards.
For falling asleep at night I also used vekham's idea of listening to music, or a shiur or audio book. something which you are interested in.
Hatzlacha rabah.
If you want to discuss things in the future since it sounds like we are fighting similar battles feel free to PM me.