mom & older sister in cahoots

[delight]

So, my sis is 13 years older than me. Since I've got married, I just feel my mom has kind of pushed me out somewhat and gotten even closer with my sister. She'll make out it's in my head. My sister has always been underhandedly bullying of me. For example, when I started hearing voices during my university finals , she would whisper down the phone to me and laugh, and when I confronted her on it , she said she was joking.

Yesterday evening I was over in my parents visiting for her sons birthday, she was over too , with her family. I gave in money for a bottle of wine so she bought 3 of the same , I guess one for me one for her and one for Mom. Maybe I had more than my fair share, they hid almost an entire bottle on me, when I asked for a top up. I knew they had hidden it so I kept on and, my loving sister started accusing me of rowing with her. Anyway I went to the cupboards and found they had poured it into a measuring jug, to hide it. I said I was going home, my mum denied doing then my sister started throwing up at me that she was going for a biopsy for cancer. Then she texted me saying not to worry she wouldn't be around much longer to be 'tight'. Her and my mom are just constant liars and I'm sick of it. Any advice?