How do I handle criticism from my boyfriend's family?

I have problems with being criticized a lot. I am white and my boyfriend is Hispanic. We have been dating for about 3 years now and get along great; we plan to marry someday. The problem is with his family. I am very reserved, and so is my family. His family is open, touchy, argumentative, and generally makes me uncomfortable.

They constantly criticize me (both in front of me in Spanish, which I can speak more than they know, and behind my back) for being “cold” and “aloof”. It really hurts, because I have genuinely tried to be more open, even hugging them (which my family never does with each other).

I have told them many times that I am trying to be friendly, but they never believe me. I am simply uncomfortable with people shouting around me and always trying to touch me.

What can I do? The criticism is starting to get to me and my boyfriend and I have been having lots of fights lately about it.