My wife refuses to find new homes for her 20+ cats. What should I do?

I am not totally blameless in this. About ten years ago I bought her a kitty. Who could see this coming. The house seems to be a magnet for strays, which my big-hearted wife always seems to take in. Due to the high volume of treating feline afflictions, fixing cat injuries & of course sterilizing the little buggers that the local vet does for my wife, she has actually has a veterinary credit card. Despite this access to medical procedures, it is not unusual for a new litter of kitties to be on the way. The grand total was around 30, but a few months ago several were lost to the busy road in front of our home. My wife gets upset when i try to discuss this problem with her. She always says,"I'm taking care of it". She has been saying tis clear back when there was only 4 cats. If she would keep them out of the house it would be an improvement. I don't want to go into the gruesome details. It seems that she is steadfast in her position. I feel that she puts the cats ahead of her family.