Seniors, your help is needed here..!?

This may be hard for you to do but the only way to deal with in laws like that is to be as cold and impersonal to them as they are to you. Eventually you will find ways not to go with him when he goes to visit his relatives. Believe me they will get the message loud and clear. Your husband should be backing you up, not his Sisters. You sound like you are plagued by Cinderella's evil step sisters.