Yeah....my mom ran into the same problem, but with 3 cats instead of one. There was a wild female that she fed sometime and my mom had two outdoor kittens. She didn't think the kittens were old enough to get preggo, so she didn't get them spayed, and then in one week, both of her cats and the wild cat had kittens in our shed. She had 14 cats after that. The ones that stuck around (sadly some didn't make it) have since been given to people as barn cats or something along those lines....but she isn't ever going to have a cat that isn't fixed again!!!

I hope your cat's little boy toy next door leaves her (and you) alone soon! The water balloon idea isn't such a bad one.....