How to deal with my snitch cousins?

Okay, I'm 15. I have three younger cousins. One of them is going to be 14 in July, the other one is 10, and the youngest is 6. They are MAJOR tattletales. They told on my brother (age 11) for touching the TV screen and saying the word stupid. Wtf??? Just yesterday, I did something really stupid. I got frustrated and said the word "fu*k!" to myself. I quickly apologized for it, and they still squealed on me. My mom took my phone away and she won't let me have it back until Friday morning. I was irresponsible, and I learned from my mistake. But how do I explain to them that no one likes a snitch? I've tried telling them that they won't have any friends if they snitch and that no one will like them. There's a difference between telling a teacher, "Johnny brought a gun to school," and "Johnny called me stupid." They always try to get me and my brother in trouble. My brother loves me and he thinks it's ridiculous what my cousins are doing. My younger cousin (the one turning 14) is going to be a freshman in high school next year. I'm going to be a sophomore. How can I get her to realize that she will see and hear things way worse? Sorry if this is so long, I'm just angry that they use everything they can to throw me under the bus.