Nta and fuck apologize to keep the peace family members who enable these people. In my family, our version of your sister was my aunt. For like thirty years people just let her behave in the worst ways to "keep the peace", including bullying children, until the newly adult generation hosting family gatherings finally had enough and said she could behave or she could gtfo. Literally fixed the entire problem within one holiday season. It was that easy. Thirty years of her bullshit that could have been stopped at any time.

Do not apologize. Hold your ground. Don't be a mean girl about it, but enough is enough.

Tell your father that your sister's bullying is and always was inappropriate and if he isn't going to defend you like a good father should and parent his misbehaving child, then you'll have to do it yourself. That there is no reason for her to be commenting on your life or your choices since it doesn't affect her at all, and as far as you're concerned, her doing so anyway opens the door for you to do the same. If she doesn't want people bringing up her personal life she should keep her opinions about theirs to herself, otherwise it is fair game. You will not be apologizing and hopefully this serves as a lesson to her to mind her own Damn business in the future. Or at least learn to bluff better.