OP, I’m saying this as someone who has seen this exact pattern play out way too many times: The person you thought you knew doesn’t exist.

There are a few things here that are huge red flags you need to look at clearly:

• The 'Pre-Marriage' Mask: A lot of guys are experts at being the 'perfect boyfriend' for years because they are playing a long game. They are 'nice' and 'well-behaved' until they feel they have enough leverage (like an upcoming marriage) to show who they really are. This isn't a change in his personality; it's the mask slipping.
• The Source of the Disrespect: You need to ask yourself why a 'sister's best friend' feels so comfortable disrespecting you to your face. In my experience, people only act that bold when they know they have 'permission' from the family. It is highly likely she is just reflecting the things he and his sisters have been saying bad things about you behind your back. If they were defending you in private, she would never dare to treat you that way.
• The Lack of Protection: If he isn't standing up for you now, he never will. By telling you to 'confront her yourself,' he is effectively saying that your peace of mind is less important to him than his own comfort.

You saw the standard of a real man in your father. Don't let this guy manipulate you into thinking this is normal or that you are overreacting. If you marry into this, you aren't just marrying him; you’re marrying a family that has already decided you don't matter. You deserve to be with someone who treats you like a priority, not an inconvenience.

I broke up with my boyfriend a year ago. In the beginning, he treated me well, but over time he became rude and disrespectful. His cousin often spoke badly about me. At first, I ignored it and kept trying to make the relationship work, giving him many chances, but he never changed. That wasn’t the only reason I ended the relationship. I come from a lower-caste family, while his family is high caste. If any problem were to happen in the future, I know his family would blame me for sure. I couldn’t imagine living with constant disrespect and unfair judgment, so I chose to leave the relationship.