Your family should be your soft place to fall, filled with cheerleaders who have your back no matter what. Unfortunately, it doesn't always work out that way. Sometimes your family can make it really hard to love them, and even harder to like them. You may come to a point when you realize nothing you do is ever good enough for a hypercritical sister, and no matter how hard you've tried, you can't break out of the mold she decided for you years ago. If you want to make your relationship work, you must take a pro-active approach rather than wait for her to change.
Don't take the criticism personally. Overly critical people find it easier to spot the flaws in others rather than do the emotional work needed to fix what they dislike about themselves. Often she is simply projecting what she dislikes about herself into you. It isn't about you at all, which means there is nothing you can do to earn her approval. It's no longer your responsibility to try; don't take on her problem as your problem.
Listen to the intent behind the words. Perhaps her heart is in the right place, but she hasn't enough tact to convey what she feels without it coming out as judgmental or critical. Instead of having a knee-jerk reaction of anger or offense, take a moment to reflect on her true motivation. Use what constructive criticism you can, and discard the rest.
Tell her how her words make you feel. Judgmental people may not even realize they are being hurtful, and instead think they are being helpful in a more direct way. Instead of letting resentment fester, set boundaries in how you interact with each other.
Minimize the damage by avoiding those topics or situations where she is most critical or judgmental. If she has made it clear she will not change, it is up to you to amend your own behavior. Rather than ask for her opinion on subjects such as your love life or your parenting abilities, keep the subjects light so you can steer clear of sensitive areas.
Limit your contact with her if the behavior continues to cause you emotional distress. You cannot change her, and if all your attempts to keep it cordial fail, then you can keep your distance for your own well-being. Instead, keep the lines of communication open through your family and be cordial at family events rather than deal with her one-on-one.