BIG decision...

So I am not a cat person, but my house use to have mice. So my mom gave me her cat "kitty" (Kitty is a boy and he is lazy lazy); and when I got married, a good friend gave me a kitten and her name is "maui". LONG story short, I walked in after being gone for the whole weekend and found out (quite scarringly) that Maui is no longer a toddler, but is now interested in boy kitties. So I kicked Kitty out of the house which I hate to do because I like him better (not much of a people cat) but Maui is not use to going outside and will probably get eaten. So I either have to get her fixed or throw her outside. Any advice?