I'm thinking of disowning my pregnant sister after our mom dies
What would make you disown your sister especially while pregnant?
It's the same reason again and again: I hate her. She bothers me and always lies to me.
I'm sorry that is how you are feeling. It can be OK to not always get along with family members every now and then. I know things may be rocky with your sister, but you shouldn't desert her while she is pregnant.
I don't think anyone listens to my problem.
Have you tried talking to your sister and telling her how you feel? Let her know how important she is to you and that you want your relationship to get better.