First- she’s 15. Fifteen years of experience on this planet. Perhaps your mother doesn’t put a lot of weight on the opinion of a 15 year old? I don’t. Particularly a 15 year old who has no real clue about relationships and specifically her parents relationship. No one but the two involved ever have the complete picture. Almost all kids/teens are a bit spoiled and selfish because they really have no clue about what it takes to provide for them. I was, my nephews are, my kids are. My eldest texted me recently to apologize about some minor things from her childhood because now that she’s older she has a different perspective.
Your sister is also manipulative and knows how to push buttons and she likes to spin people up. Sit down and assess yourself, as others said you can only control yourself, and honestly consider what ‘hot buttons’ you have. Desensitize yourself to them- your reaction to your sister is her reward/motive. Don’t react in the way she desires. Ignoring folks who want drama and refusing to participate disarms them. Pity her, how sad and miserable she must be to have to lash out, to seek some kind of joy and satisfaction in other people’s pain. Pray for her.
You can certainly hate/deplore her behavior. You obviously can not respect people behaving in a way that isn’t respectable. But, you should hope and pray for her emotional and spiritual growth, for her to see the error of her ways.
My wife walked out of our 21 year marriage. I hate the fact she did that, I hate what it has done to the kids (they live/lived with me), but seriously, I don’t hate her. I pray for her, she wasn’t happy, I couldn’t figure out how to ‘make’ her happy and wanted her to stay. How could I honestly tell you she was horrible and I hate her if I wanted her to stay? Is that in some way what you feel about your Dad? If you want him there, if you would prefer he hadn’t done what he did so you could still be together than I don’t think you truly hate him, you hate his choices, what he’s done, and what it reveals about his character. Pity a man who has given up the opportunity to kiss his children every morning and put them to bed at night. Pity him for the times he will miss with you and your sister. He will never be able to recover that. All those little moments and memories that make a life worthy of living. He’s human, he has weaknesses as all of us do.
Try and enjoy the little things in life. Try to bring focus on the things that bring you happiness and enjoyment. Appreciate all the things you do have and treasure them- the ability to write, the ability to see, the ability to take a deep breath, your time with your Mom (you’ll move out and miss her someday), the colors in a flower, your faith, your health.
It is wrong to hate people. A priest told my mom that Jesus said we have to love everyone, but he didn’t say we have to like them. Don’t confuse not approving of bad behavior, or hatred of deplorable conduct, with hatred of the person.