WHAT CAN I DO ABOUT NEIGHBOR FEEDING STRAY CATS!?

It started off as my neighbor having just one cat when we moved in... (we live in the main house, and they live in this little mother-in law type house at the end of our driveway... its a tiny shack, they basically live in our garage XD) but recently, she's been feeding her cat outside AND A LOT OF FOOD, and that's attracted more cats... now there is atleast a dozen cats hanging around my freiking house! it's horrid, they f**king STINK THE DAMN PLACE UP! I can't even open my windows or my doors without the smell of cat urine flooding in, the cats are climbing all over my vehicles and chillin on my porch all day, i think they're pissing on my door mat because it smells really strong right there... but at any given moment i can look out back and have 10 cats in my back yard and they have **** EVERYWHERE back there. THEY KEEP PISSING ON MY PORCH i can't even hang out outside my own fkn house or work on my cars out there because it smells so fkn bad! wtf can i do? they STAY sleeping on my truck, and under my car, and on my porch, on top of the trash cans, i'm like 24 hours from unloading my 12GA on them because i can't stand this s*it anymore. they're always out their fighting and meowing and s*it late at night right by my window. i'm being bullied by some little cats in my own home and it's getting real old...