am i wrong to want nothing to do with my sister?

so my sister an i have always been close like best friends we use to do everything together well 3 years ago she met this sheriffs deputy an ever since then she thinks shes better then everybody so does he they have money so they like to show it off well lately we been fighting ever since i got pregnant an i cant take the stress anymore i have a lot of anxiety since i was little but now that im pregnant its gotten worse an my sister an her husband make it worse they are trying to control me even when i babysit there kids her husband starts yelling at me jus for talking to my mom they tell me to stop being a bitch an my mom couldnt believe it that they were saying that i couldng believe it cause anybody that knows me knows im a good sweet person an i do what i can for my family but after they said that i started crying an her husband came to me an said thats how family talk to each other my mom told him family doesnt talk like that to one another my dad almost fought him cause hes not only yelled at me hes done it to my brother an my mom an my brother doesnt have nothing to do with them cause of my sisters husband my sister sticks up for him all the time but my sister is worse jus because my mom wanted to help one of are neighbors out my sister got mad an the next day didnt wish my mom a happy bday an my mom is dying i have to hear my mom cry all the time cause of how my sister is im fed up with it all so ive decided that im done with them an they arent apart of my babys life an i no this is bad but i hate both of my sister an her husband i always looked up too my sister but i dont anymore i want them out of my life so i told them that they will not be a apart of it anymore was i wrong to do it or was i right?i jus dont want the stress or drama an they have really made me really unhappy this whole pregnancy so far an i shouldnt feel that way i should be happy :(