Hello everyone

My name is sarah and this is my first time posting on POTD.
I have found myself in a troubling situation regarding my mom, and I literally cannot do this alone.
My mom started out having only a couple of cats, but we were in a neighborhood where there were a small handful of fixed strays that a few of the neighbors would feed. Well, in the past year, all the other neighbors that had been feeding the neighborhood cats moved away, and new neighbors have moved in that hate cats, and loudly talk at night about how they wish they could kill all the cats in various ways.
Anyway, there was one ferile cat that nobody could catch, whom the neighborhood dubbed "mamacat" with good reason. She had 2 litters of kittens before we could trap her and have her fixed. Also, in between her 2 litters, one of my cats(that had been rescued as a kitten and was still very young, so we hadnt thought to fix her yet) had a litter.
So, practically all at once, we had around twenty cats.
As soon as they were old enough, we had them all fixed and given shots, (which would have been impossibly expensive had we not found the right people-with-a-purpose..)
Only now that everyone is fixed, they have pretty much invited themselves in and scratch at the door and cry to be let it, and my mom doesn't have the heart to reject them, so she spends all of her energy and money making sure these cats have a home. She is a single mom, and in the past year (especially the past couple months, now that the kittens have gotten a little bigger) I have watched her struggle with this situation more and more.
My mom keeps a nice home, but it is too much work for her, and I am afraid that once the cats are full grown, she will really lose her mind from the stress of it. It is so hectic, and I am constantly worried about our neighbors doing something to harm them.
I am so afraid for my mother's happiness, and the safety of our feline family members, that it is impossible for me to be happy myself. My boyfriend and I have agreed to take 3 cats, but we cannot take any more. My mom would not tolerate the idea of putting them in a shelter to be caged, when she offers them a loving home.
I hate the idea myself. But even if I take 3, there is hardly even a dent in this problem.
I know everyone on this site is a trustworthy person when it comes to caring for animals, and I must say that I need your help.

Please, if you are considering adoption, or if you know anybody that could offer a loving home, consider me. All cats are fixed and have had shots, and are all litter box trained. None are completely full grown, but all are very affectionate and have vivid, wonderful personalities.
we do suggest or prefer that they go in pairs, because they are very attached to each other, or at least used to having lots of company....

Thank you.