I understand your struggle. Do you see a therapist? When I was dealing with a difficult family member, I got some good advice from a therapist I had at the time. I recommend you find a therapist ASAP

In general when dealing with difficult, rude and disrespectful family member advice is to minimize contact IF full no contact/estrangement isn’t possible. And going “no contact” with close family member is often too complicated. Some people advise to cut family members off but I know it’s too complicated as it affects other family members who aren’t at fault.

So instead you do “low contact”: keep your interactions to a minimum. Conversations and get togethers should be short and infrequent. Practice “grey rock”. Don’t get engage in fights or back and forth. When they start arguing go about your things or end the conversation. “Ok got to go. Bye”. Have strong boundaries without being argumentative.

Now most certainly no one would ever advise to go on vacation with a difficult family member. Why? No way. I get along with my brother but I have no desire to go on vacation with bunch of people. Just travel with your husband. Maybe take your mom. Traveling with your sister who is rude to you both (plus she has her friends there) is unnecessary

I fully understand cultural differences and understand traditional family values etc But even in the most traditional cultures people stand by their spouse. Wife is expected to emotionally support her husband, rather than sister. I understand cultural obligation (in many cultures) to take care of elderly parents but I haven’t heard of cultural obligation of allowing disrespect from a rude sibling.

If you don’t have a therapist, but belong to organized religion of any sort, maybe go talk to your religious leader and ask what they think it’s a good course of action. I suspect they’ll advise you stand by your husband, not your sister.

When you marry, you supposed to “leave your home”. It doesn’t mean you must ignore your extended family. No. But it means your first allegiance is with you immediate family: spouse and kids. If you plan on having children, it won’t be good for them to witness their parents being disrespected by a sibling and their mom putting her sister first. I suspect that she’ll disrespect your kids too if you decide to have them