Hang them up on the washing line outdoors in dry, windy weather.
Unfortunately, it takes ages to get rid of the smell of tom cat, and I assume as he was spraying and is bossy that he is not neutered, from things, you cannot wash.
Even when you no longer can smell tom-cat on your boots, your own cats will stil be able to, so keep those boots where they can't reach them, or they may, even if neutered or female, wee on them in protest at the smell.
If you can find a shoemaker, saddle-maker on any other professional who works in leather you could ask if they know of anything you safely can use on the boots to get rid of the smell. I have a feeling that some of the chemicals used in tanning leather might do the trick, but don't know which ones or even if you can buy them over the counter.