My mom wants to get rid of my cats?

So my mom is not a cat person, but she got our oldest cat back in 2000, when I was 3 or 4. We then found our other cat in 2008 or 9, as a little tiny kitten. Milo, the older cat, does not always use the litter box. Rhoda breaks stuff sometimes, but that is getting much better now that I got her some cardboard she can claw and other outlets for her boredom. My cats live in my room during the day and only have free reign of the house at night time, because two of the dogs are not very nice with them, so it is for their own safety until the dogs are in bed. My mom absolutely hates the cats. Any time they do something wrong, she is like "Okay, we are getting rid of them." Or, "Why don't you just get rid of them?". For example- I am breeding bettas. I had a gorgeous silver crowntail male in my room. Most of my fish are perfectly safe- the bowls and tanks cannot be dropped, the lids are secure, the male cat doesn't care about them, and my female can safely watch them. It's like tv for her, and she is not harming them. But that silver male I had died at her claw because I had him in a different tank that I hadn't used in my room yet. I didn't think she could lift the lid, but that is exactly what she did and she wound up eating him when I wasn't home. I was sad but it taught me that I really need to make sure the lids are taped or clamped securely, so I have to work to get in the tanks, never mind the cat. My mom told me that if I get rid of her, I won't have to worry about it. That is true, but I absolutely love my little cat. She is a sweetheart and she talks to me when I get home and she curls up with me and she is just a little lovey. But little things happen all the time and my mom's threats of getting rid of them are more and more severe and common. I am nearly 17. In a little over a year, I will be 18. When I am 18, if it is what I need to do, I will move out and in with a friend or if I have enough money saved up by then, an apartment or something, and I will take my cats and my sheltie with me. Likely my fish too but that is a problem to deal with when the time comes. Bottom line- my mom will not /have/ to put up with my cats for much longer. How can I hold on to them for until I can get them out myself? How can I convince her to let them be and not just take my pets and rehome them while I am at school or something? I've even considered moving in with some family friends with my pets who would like to take me in if she insists- then they are out of her way and I am as well to not screw everything up all the time anyways, so it is win win to my mom, but I would rather not do that. I would rather stay put until I am 18 or a little longer- till I am graduated from high school.